CN113013260B - Photosensitive SiC heterogeneous junction multi-potential-barrier varactor - Google Patents

The invention discloses a photosensitive SiC heterojunction multi-barrier varactor which comprises N arranged in sequence ⁺ Type 3C-SiC substrate, at least one set of heterogeneous junctions, N ⁺ A type 3C-SiC contact layer; the heterogeneous junction is composed of an N-type 3C-SiC modulation layer, an intrinsic 4H-SiC or 6H-SiC barrier layer and an N-type 3C-SiC modulation layer, wherein in the heterogeneous junction, the N-type 3C-SiC with a narrow band gap is a potential well, and the intrinsic 4H-SiC or intrinsic 6H-SiC with a wide band gap is a potential barrier; a silicon dioxide protective layer is generated on the surface of the isomeric structure, and a shading layer is coated outside the silicon dioxide protective layer; said N is ⁺ Type 3C-SiC substrate, N ⁺ Ohmic electrodes are respectively arranged on the outer surfaces of the type 3C-SiC contact layers; n is a radical of ⁺ And the outer surface of the type 3C-SiC contact layer is provided with a light hole. The invention has the advantages of small leakage current, small capacitance, high cut-off frequency, wide dynamic load modulation range and capacity change by illumination; it is suitable for frequency doubling, parameter amplification, light detection, etc.

一种光敏型SiC异构结多势垒变容二极管A photosensitive SiC heterojunction multi-barrier varactor diode

技术领域technical field

本发明属于电子技术领域，具体是涉及半导体固态高频器件，特别是指光敏型SiC异构结多势垒变容二极管。The invention belongs to the technical field of electronics, in particular to a semiconductor solid-state high-frequency device, in particular to a photosensitive SiC heterogeneous junction multi-barrier varactor diode.

背景技术Background technique

相对于其它半导体材料，SiC因为临界击穿场强高，对反向击穿电压要求相同时，SiC制备的器件中材料掺杂可以更高，因此SiC器件的固有内阻小；SiC的热导率、饱和电子迁移率高，适用于高温、高频器件；3C-SiC的带隙E_g＝2.39eV，与绿光光子能量相当，可以吸收绿光；4H-SiC、6H-SiC的带隙分别为E_g＝3.26eV、E_g＝3.02eV，可以吸收紫光。立方相3C-SiC与六方相4H-SiC、6H-SiC分别形成界面两侧成份相同、结构不同的3C/4H-SiC、3C/6H-SiC异构结势垒。异构结势垒变容二极管在结构上、原理上不同于pn结变容二极管、肖特基结变容二极管、金属/半导体/金属(MSM)结变容二极管、金属板变容器。可以预见，3C/4H-SiC、3C/6H-SiC异构结势垒变容二极管将具有高温、高频、大功率的优势，对绿光、近紫外光敏感。相对于变阻二极管，变容二极管具有较高的转换效率。Compared with other semiconductor materials, due to the high critical breakdown field strength of SiC, when the reverse breakdown voltage requirements are the same, the material doping in the device prepared by SiC can be higher, so the inherent internal resistance of SiC device is small; the thermal conductivity of SiC It is suitable for high temperature and high frequency devices; the band gap of 3C-SiC is E _g = 2.39eV, which is equivalent to the photon energy of green light and can absorb green light; the band gap of 4H-SiC and 6H-SiC They are E _g =3.26eV and E _g =3.02eV respectively, which can absorb violet light. The cubic phase 3C-SiC and the hexagonal phases 4H-SiC and 6H-SiC respectively form 3C/4H-SiC and 3C/6H-SiC heterojunction barriers with the same composition and different structures on both sides of the interface. Heterogeneous junction barrier varactors are different in structure and principle from pn junction varactors, Schottky junction varactors, metal/semiconductor/metal (MSM) junction varactors, and metal plate varactors. It is foreseeable that 3C/4H-SiC and 3C/6H-SiC heterogeneous junction barrier varactor diodes will have the advantages of high temperature, high frequency and high power, and are sensitive to green light and near-ultraviolet light. Compared with varistor diodes, varactor diodes have higher conversion efficiency.

通过检索，已有反映变容二极管的技术文献，主要为：Through the search, there are technical documents reflecting the varactor diodes, mainly as follows:

文献1[Status and prospects of high-power hetero-structure barriervaractor frequency multipliers,Proceedings of the IEEE,Vol.105,No.6(2017):1008-1019.]反映，异质结势垒变容二极管的势垒应该足够高，阻止热电流和隧穿；相对于量子级联激光器，异质结势垒变容二极管可以常温下工作，具有更高的功率、效率、可调性，信号具有更窄的线宽；相对于肖特基势垒变容二极管、耿氏(Gunn)二极管，异质结势垒变容二极管具有更高的功率、效率，因为可以通过增加势垒来提高耐压、降低漏电流；最大输出功率受限于异质结势垒高度、最大电流密度、最高结温和电路阻抗。此综述文章其中没有光敏型SiC异构结势垒变容二极管的相关信息。Document 1 [Status and prospects of high-power hetero-structure barrier varactor frequency multipliers, Proceedings of the IEEE, Vol.105, No.6(2017):1008-1019.] reflects that the potential of the heterojunction barrier varactor diode The barrier should be high enough to prevent thermal current and tunneling; compared with quantum cascade lasers, heterojunction barrier varactors can work at room temperature, with higher power, efficiency, tunability, and narrower signal lines Wide; compared with Schottky barrier varactors and Gunn diodes, heterojunction barrier varactors have higher power and efficiency, because the barrier can be increased to improve withstand voltage and reduce leakage current ; Maximum output power is limited by heterojunction barrier height, maximum current density, maximum junction temperature and circuit impedance. There is no information on photosensitive SiC heterojunction barrier varactors in this review article.

文献2[Efficient hetero-structure doped-barrier varactor diodes,Journal of Applied Physics,Vol.105,No.2(2009):024502-1-5.]研究了In_0.53Ga_0.47As/AlAs和InN/GaN同质结的势垒施主型掺杂对变容二极管的电容调制比(最大、最小电容之比C_max/C_min)、三次谐波(A₃/A₁)倍增效率的影响，势垒掺杂高于一定程度时不再限制势阱层的屏蔽长度，杂质电离形成自由电荷，导致变容二极管的C_max值增大，C_min值不受势垒掺杂的影响，因此电容调制比增大；三次谐波与基波振幅之比(A₃/A₁)由势垒不掺杂时的45％提高到势垒掺杂时的65％。Document 2 [Efficient hetero-structure doped-barrier varactor diodes, Journal of Applied Physics, Vol. 105, No. 2 (2009): 024502-1-5.] studied the same properties of In _0.53 Ga _0.47 As/AlAs and InN/GaN The influence of the barrier donor type doping of the mass junction on the capacitance modulation ratio (the ratio of the maximum and minimum capacitances C _max /C _min ) and the multiplication efficiency of the third harmonic (A ₃ /A ₁ ) of the varactor, the barrier doping Above a certain level, the shielding length of the potential well layer is no longer limited, and impurities are ionized to form free charges, resulting in an increase in the C _max value of the varactor diode, and the C _min value is not affected by the potential barrier doping, so the capacitance modulation ratio increases ; The ratio of the third harmonic to the fundamental amplitude (A ₃ /A ₁ ) increases from 45% when the barrier is not doped to 65% when the barrier is doped.

文献3[Balanced MSM-2DEG varactors based on AlGaN_GaN hetero-structurewith cutoff frequency of 1.54THz,IEEE Electron Device Letters,Vo.38,No.1(2017):107-110.]研制了Al_0.24Ga_0.76N/GaN异质结金属/半导体/金属-二维电子气(MSM-2DEG)型变容二极管，利用金属有机物化学气相沉积(MOCVD)技术，在SiC衬底上从底到顶逐次生长AlN核化层、1.8μm厚Fe掺杂的GaN过渡层、22nm厚Al_0.24Ga_0.76N肖特基势垒层、3nm厚GaN接触层；制作了对称栅(2个T形栅)、非对称栅(1个T形栅+1个矩形栅)、平衡栅(1个T形栅+左右各1个矩形栅)结构电极；比较了对称栅、非对称栅、平衡栅结构的电阻和电容，后2者因为接触面积大减小了接触电阻，平衡栅结构还减小了2DEG的沟道电阻，后2者中T形栅减小了高频电阻但增大了边沿电容(最大电容C_max)；变容二极管的截止频率(f_T)提高到1.54THz，电容调制比(最大、最小电容之比C_max/C_min)增加到2.64，质量因素(FOM)达到4.06THz。Literature 3 [Balanced MSM-2DEG varactors based on AlGaN_GaN hetero-structure with cutoff frequency of 1.54THz, IEEE Electron Device Letters, Vo.38, No.1(2017):107-110.] developed Al _0.24 Ga _0.76 N/GaN Heterojunction metal/semiconductor/metal-two-dimensional electron gas (MSM-2DEG) type varactor diode, using metal organic chemical vapor deposition (MOCVD) technology to grow AlN nucleation layer from bottom to top on SiC substrate, 1.8 μm thick Fe-doped GaN transition layer, 22nm thick Al _0.24 Ga _0.76 N Schottky barrier layer, 3nm thick GaN contact layer; fabricated symmetrical gates (two T-shaped gates) and asymmetric gates (one T-shaped gate Grid + 1 rectangular grid), balanced grid (1 T-shaped grid + 1 rectangular grid on the left and right) structure electrodes; compared the resistance and capacitance of the symmetrical grid, asymmetric grid, and balanced grid structure, the latter two are due to the contact area. The contact resistance is greatly reduced, and the balanced gate structure also reduces the channel resistance of the 2DEG. In the latter two, the T-shaped gate reduces the high-frequency resistance but increases the edge capacitance (maximum capacitance C _max ); The cut-off frequency (f _T ) is increased to 1.54THz, the capacitance modulation ratio (the ratio of the maximum and minimum capacitances C _max /C _min ) is increased to 2.64, and the quality factor (FOM) reaches 4.06 THz.

文献4[High-performance 450-GHz GaAs-based hetero-structure barriervaractor tripler,IEEE Electron Device Letters,Vo.24,No.3(2003):138-140.]研制了Al_0.7Ga_0.3As/GaAs异质结势垒变容二极管(HBV)，利用分子束外延(MBE)技术，在半绝缘GaAs衬底上从底到顶逐次生长GaAs过渡层、Al_0.7Ga_0.3As刻蚀阻挡层、n⁺型GaAs欧姆接触层、250nm厚n型GaAs调制掺杂层/3.5nm厚不掺杂GaAs间隔层/Al_0.7Ga_0.3As势垒层/3.5nm厚不掺杂GaAs间隔层/500nm厚n型GaAs调制掺杂层，其中，调制掺杂层/间隔层/势垒层/间隔层/调制掺杂层——异质结4个周期；在介电薄膜上制作了平面传输线波导(150GHz带阻+450GHz带通)，无需空气桥，利用芯片倒装技术减少寄生损耗；测量发现，在频率451.8GHz时最大功率1.05mW，效率1.3％，最大摆幅效率1.45％。Literature 4 [High-performance 450-GHz GaAs-based hetero-structure barriervaractor tripler, IEEE Electron Device Letters, Vo.24, No.3(2003): 138-140.] developed Al _0.7 Ga _0.3 As/GaAs heterogeneity Junction barrier varactor diode (HBV), using molecular beam epitaxy (MBE) technology to grow GaAs transition layer, Al _0.7 Ga _0.3 As etch barrier, n ⁺ type GaAs ohmic layer from bottom to top sequentially on semi-insulating GaAs substrate Contact layer, 250nm thick n-type GaAs modulated doped layer/3.5nm thick undoped GaAs spacer layer/Al _0.7 Ga _0.3 As barrier layer/3.5nm thick undoped GaAs spacer layer/500nm thick n-type GaAs modulated doped layer layer, among which, modulation doped layer/spacer layer/potential barrier layer/spacer layer/modulation doped layer—heterojunction 4 cycles; planar transmission line waveguide (150GHz band-stop + 450GHz band-pass) was fabricated on the dielectric film ), no air bridge is needed, and the parasitic loss is reduced by flip-chip technology; it is found that the maximum power is 1.05mW, the efficiency is 1.3%, and the maximum swing efficiency is 1.45% at a frequency of 451.8GHz.

文献5[SiC varactors for dynamic load modulation of high poweramplifiers,IEEE Electron Device Letters,Vol.29,No.7(2008):728-730.]在分析C-V关系的基础上，利用热壁化学气相沉积(HWCVD)技术在N⁺型SiC衬底上生长一层氮掺杂依(1+ax)^-3规律变化的SiC外延膜，并在SiC薄膜上蒸镀

肖特基接触电极，形成SiC同质结肖特基势垒变容二极管。按照(1+ax)^-3规律梯度掺杂可以增加C-V关系的线性和调谐范围，调制比超过10；SiC的高临界击穿电场能够在同样的电压要求下提高掺杂水平，得到低的损耗和高的品质因子。通过阳极自对准工艺，避免阳极边沿电场集中而提高击穿电压，不需要付出为了提高击穿电压而降低掺杂从而增加损耗的代价。此研究文章没有光敏型SiC异构结势垒变容二极管的阐述。Literature 5 [SiC varactors for dynamic load modulation of high poweramplifiers, IEEE Electron Device Letters, Vol.29, No.7(2008):728-730.] On the basis of analyzing the relationship of CV, using hot wall chemical vapor deposition (HWCVD) ) technology to grow a layer of SiC epitaxial film with nitrogen doping according to (1+ax) ^-3 law on N ⁺ type SiC substrate, and evaporate it on the SiC film

The Schottky contact electrode forms a SiC homojunction Schottky barrier varactor. Gradient doping according to the (1+ax) ^-3 law can increase the linearity and tuning range of the CV relationship, and the modulation ratio exceeds 10; the high critical breakdown electric field of SiC can increase the doping level under the same voltage requirement, resulting in low loss and high quality factor. Through the anode self-alignment process, the electric field concentration on the edge of the anode is avoided to increase the breakdown voltage, and there is no need to pay the price of reducing the doping and increasing the loss in order to increase the breakdown voltage. This research article does not describe photosensitive SiC heterojunction barrier varactors.

文献6[Some rules for the choice of the C(V)characteristic for thedesign of frequency triplers with symmetrical varactors,2002IEEE MTT-SInternational Microwave Symposium Digest,Vol.1,No.1(2002):359-362.]预测，电容-电压关系具有余弦对称、电流-电压关系具有奇对称特征的异质结势垒变容二极管，在载波转换成3倍频谐波时具有最高的能量效率。此文献不涉及光敏型SiC异构结势垒变容二极管。Reference 6 [Some rules for the choice of the C(V)characteristic for the design of frequency triplers with symmetrical varactors, 2002 IEEE MTT-S International Microwave Symposium Digest, Vol.1, No.1(2002):359-362.] predicts that, Heterojunction barrier varactor diodes with cosine symmetry in the capacitance-voltage relationship and odd symmetry in the current-voltage relationship have the highest energy efficiency when the carrier is converted to 3 harmonics. This document does not deal with photosensitive SiC heterojunction barrier varactors.

文献7[Hetero-barrier varactors with nonuniformly doped modulationlayers,Technical Physics Letters,Vol.45,No.10(2019):1063-1066.]利用记入电荷密度梯度的量子漂移-扩散模型，设计了电容-电压关系具有对称余弦、电流-电压关系具有奇对称特征的InAlAs/AlAs/InAlAs异质结势垒变容二极管，并采用分子束外延(MBE)技术在InP衬底上制备了此器件。结果表明，排除MBE工艺中掺杂突变的影响，测试的电容-电压、电流-电压关系与设计的情况吻合；此模型适用于设计任意组份、任意掺杂的异质结势垒变容二极管。此研究文章没有光敏型SiC异构结势垒变容二极管以及SiC异构结界面二维电子(空穴)气的阐述。Reference 7 [Hetero-barrier varactors with nonuniformly doped modulationlayers, Technical Physics Letters, Vol.45, No.10(2019): 1063-1066.] uses a quantum drift-diffusion model with charge density gradients to design a capacitance-voltage model The InAlAs/AlAs/InAlAs heterojunction barrier varactor diode with symmetric cosine relationship and odd symmetry in the current-voltage relationship was fabricated on InP substrate by molecular beam epitaxy (MBE). The results show that the measured capacitance-voltage and current-voltage relationships are consistent with the design, excluding the influence of doping mutation in the MBE process; this model is suitable for the design of heterojunction barrier varactors with arbitrary components and arbitrary doping. . This research article does not describe the photosensitive SiC heterojunction barrier varactor diode and the two-dimensional electron (hole) gas at the SiC heterojunction interface.

文献8[MSM varactor diodes based on In_0.7Ga_0.3As HEMTs with cutofffrequency of 908GHz,IEEE Electron Device Letters,Vol.35,No.2(2014):172-174.]利用埋Pt栅技术研制了栅长度、栅-沟距离可变的InP/In_0.52Al_0.48As/In_0.7Ga_0.3As/In_0.53Ga_0.47As异质结HEMT结构的MSM-2DEG变容二极管。此器件的电容开关比既依赖于电极结构又依赖于垂直层结构，它的设计自由度比SB变容二极管的多。减少栅-沟道距离可显著改善器件的FOM值，压缩栅长度可提高截止频率而保持同样的FOM水平，退火后器件的开关电容比、FOM值增加。此文献与光敏型SiC异构结势垒变容二极管没有关联。Document 8 [MSM varactor diodes based on In _0.7 Ga _0.3 As HEMTs with cutofffrequency of 908GHz, IEEE Electron Device Letters, Vol.35, No.2(2014): 172-174.] developed the gate length, MSM-2DEG varactor diode with InP/In _0.52 Al _0.48 As/In _0.7 Ga _0.3 As/In _0.53 Ga _0.47 As heterojunction HEMT structure with variable gate-to-channel distance. The capacitance-to-switch ratio of this device depends on both the electrode structure and the vertical layer structure, and its design freedom is more than that of the SB varactor. Reducing the gate-channel distance can significantly improve the FOM value of the device, compressing the gate length can increase the cut-off frequency while maintaining the same FOM level, and the switched capacitance ratio and FOM value of the device after annealing increase. This document is not related to photosensitive SiC heterojunction barrier varactors.

文献9[Anomalous capacitance enhancement triggered by light,IEEEJournal of Selected Topics in Quantum Electronics,Vol.21,No.4(2015):3800605-1-5.]设计了引入二维空穴气(2DHG)的金属/半导体(GaAs/Al_0.24Ga_0.76As/Al_0.9Ga_0.1As(15周期超晶格)/GaAs)/金属(MSM)结构变容二极管型光探测器，折衷协调光响应速度与量子效率的关系来优化光吸收层的厚度。在测量电容—电压关系时，改变入射光强度来控制超晶格中2DHG的浓度，调节该变容二极管的电容。结果表明，光照足够时临界电压处的电容增强达到200％，激发信号频率高于10kHz时峰谷电容之比大于4，光照电容与无光电容之比超过40。分析原因为，超晶格中的光生2DHG浓度在变容二极管反向偏置时发生变化，产生交换关联能，引起二维电荷系统的电容随之变化，是一种量子效应。此变容二极管可用于光电容、光晶体管、光探测器、光电耦合器等。MOS(金属/氧化物/半导体)型变容二极管中半导体等材料取代了机械式调谐电容器的金属板，使用电压调节电容，可靠性更高。此研究文章与光敏型SiC异构结势垒变容二极管无关。Document 9 [Anomalous capacitance enhancement triggered by light, IEEE Journal of Selected Topics in Quantum Electronics, Vol. 21, No. 4 (2015): 3800605-1-5.] designed the introduction of two-dimensional hole gas (2DHG) metal/ Semiconductor (GaAs/Al _0.24 Ga _0.76 As/Al _0.9 Ga _0.1 As (15-period superlattice)/GaAs)/metal (MSM) structure varactor photodetector, the relationship between light response speed and quantum efficiency is compromised. Optimize the thickness of the light absorbing layer. When measuring the capacitance-voltage relationship, the intensity of incident light was changed to control the concentration of 2DHG in the superlattice, and the capacitance of the varactor diode was adjusted. The results show that the capacitance enhancement at the critical voltage reaches 200% when the light is sufficient, the ratio of peak-to-valley capacitance is greater than 4 when the excitation signal frequency is higher than 10 kHz, and the ratio of light capacitance to no light capacitance exceeds 40. The reason for the analysis is that the concentration of photogenerated 2DHG in the superlattice changes when the varactor diode is reverse biased, resulting in exchange correlation energy, which causes the capacitance of the two-dimensional charge system to change accordingly, which is a quantum effect. This varactor diode can be used in photocapacitors, phototransistors, photodetectors, photocouplers, etc. Materials such as semiconductors in MOS (metal/oxide/semiconductor) type varactors replace the metal plates of mechanical tuning capacitors, and use voltage-adjusting capacitors for higher reliability. This research article is not related to photosensitive SiC heterojunction barrier varactors.

文献10[Photo-capacitive light sensor based on metal-YMnO3-insulator-semiconductor structures,Applied Physics Letters,Vol.108,No.5(2016):052103-1-5.]采用脉冲激光沉积(PLD)技术在P型Si上依次生长SiN_x、YMnO₃薄膜，制备成金属(Al电极)/铁电层/绝缘体/半导体MFIS型光控变容二极管。其中YMnO₃层的铁电极化在二极管正向偏置时对准SiN_x绝缘层并提高绝缘层/半导体界面的反型层少子浓度，增强光电容效应。结果表明，电容的增量可以反映光照强度、波长(蓝、绿、红、近红外等)的变化，适用于光探测器等。此文献与光敏型SiC异构结势垒变容二极管以及SiC异构结界面二维电子(空穴)气没有关联。Document 10 [Photo-capacitive light sensor based on metal-YMnO3-insulator-semiconductor structures, Applied Physics Letters, Vol.108, No.5(2016):052103-1-5.] uses pulsed laser deposition (PLD) technology in SiN _x and YMnO ₃ thin films are grown on the P-type Si in turn to prepare a metal (Al electrode)/ferroelectric layer/insulator/semiconductor MFIS light-controlled varactor diode. Among them, the ferroelectric polarization of the _YMnO3 layer aligns with the _SiNx insulating layer when the diode is forward biased and increases the minority carrier concentration of the inversion layer at the insulating layer/semiconductor interface, enhancing the photocapacitive effect. The results show that the increment of capacitance can reflect the change of light intensity and wavelength (blue, green, red, near-infrared, etc.), which is suitable for photodetectors, etc. This document is not related to the photosensitive SiC heterojunction barrier varactor diode and the two-dimensional electron (hole) gas at the SiC heterojunction interface.

文献11[Comparison of the efficiency of promising hetero-structurefrequency-multiplier diodes of the THz-frequency range,Semiconductors,Vol.54,No.10(2020):1360-1364.]通过实验和数值计算，比较了GaAs(阱)/AlAs(垒)异质结势垒变容二极管(HBVD)与GaAs(阱)/AlAs(垒)超晶格(SL)二极管的效率和信号输出比功率(单位面积输出功率)，发现两者的比功率相当，前者的效率高出后者的效率约10倍。此文献与光敏型SiC异构结以及SiC异构结界面二维电子(空穴)气(2DEG或2DHG)无关联。Literature 11 [Comparison of the efficiency of promising hetero-structurefrequency-multiplier diodes of the THz-frequency range, Semiconductors, Vol.54, No.10(2020):1360-1364.] Through experiments and numerical calculations, compared GaAs ( well)/AlAs (barrier) heterojunction barrier varactor diode (HBVD) and GaAs (well)/AlAs (barrier) superlattice (SL) diode efficiency and signal output specific power (output power per unit area), found The specific power of the two is comparable, and the efficiency of the former is about 10 times higher than that of the latter. This document is not related to the photosensitive SiC heterojunction and the two-dimensional electron (hole) gas (2DEG or 2DHG) at the interface of the SiC heterojunction.

文献12[InGaAs/InAlAs/AlAs hetero-structure barrier varactors onsilicon substrate,IEEE Electron Device Letters,Vol.32,No.2(2011):140-142.]利用分子束外延(MBE)技术生长了InGaAs/InAlAs/AlAs异质结，再利用直接键合技术键合到Si晶片上，形成异质结势垒变容二极管；与在InP晶片上直接外延生长InGaAs/InAlAs/AlAs形成的异质结势垒变容二极管进行比较，发现两者的单位面积电容——电压关系几乎相同，电容——电压曲线关于0电压对称，不受衬底影响，前者的电流密度——电压曲线关于0电压对称。此论文与光敏型SiC异构结以及二维电子(空穴)气无关。Document 12 [InGaAs/InAlAs/AlAs hetero-structure barrier varactors onsilicon substrate, IEEE Electron Device Letters, Vol.32, No.2 (2011): 140-142.] InGaAs/InAlAs were grown by molecular beam epitaxy (MBE) technology /AlAs heterojunction, and then bonded to the Si wafer by direct bonding technology to form a heterojunction barrier varactor diode; and the heterojunction barrier formed by the direct epitaxial growth of InGaAs/InAlAs/AlAs on the InP wafer. Comparing the capacitance and diode, it is found that the capacitance-voltage relationship per unit area of the two is almost the same, the capacitance-voltage curve is symmetric about 0 voltage and is not affected by the substrate, and the current density-voltage curve of the former is symmetric about 0 voltage. This paper has nothing to do with photosensitive SiC heterojunction and two-dimensional electron (hole) gas.

文献13[InGaN/GaN Schottky diodes with enhanced voltage handlingcapability for varactor applications,IEEE Electron Device Letters,Vol.31,No.10(2010):1119-1121.]利用金属有机物化学气相沉积(MOCVD)技术生长了在N型外延GaN晶片上分别生长了In_0.4Ga_0.6N、In_0.1Ga_0.9N表面层，形成了InGaN/GaN异质结肖特基势垒(SB)变容二极管，对比无InGaN表面层的肖特基势垒变容二极管，前者的击穿电压提高、漏电流降低；击穿电压提高归因于表面电场降低；因为界面极化诱导电荷，隧穿距离延长导致漏电流降低。但是，SB变容二极管的电容开关比只依赖于垂直层结构，器件设计自由度少。此文献不涉及光敏型SiC异构结以及二维电子(空穴)气。Literature 13 [InGaN/GaN Schottky diodes with enhanced voltage handlingcapability for varactor applications, IEEE Electron Device Letters, Vol.31, No.10(2010):1119-1121.] used metal organic chemical vapor deposition (MOCVD) technology to grow the In _0.4 Ga _0.6 N and In _0.1 Ga _0.9 N surface layers were grown on N-type epitaxial GaN wafers to form InGaN/GaN heterojunction Schottky barrier (SB) varactors. For the terky barrier varactor diode, the breakdown voltage of the former is increased and the leakage current is decreased; the increase in the breakdown voltage is attributed to the decrease of the surface electric field; because of the charge induced by the interface polarization, the tunneling distance is prolonged and the leakage current is decreased. However, the capacitance switching ratio of the SB varactor only depends on the vertical layer structure, and the degree of freedom in device design is small. This document does not deal with photosensitive SiC heterojunctions and two-dimensional electron (hole) gases.

文献14[ASiC varactor with large effective tuning range for microwavepower applications,IEEE Electron Device Letters,Vol.32,No.6(2011):788-790.]利用热壁化学气相沉积(HWCVD)技术在N⁺型SiC衬底上首先生长一层氢掺杂的SiC间隔层，再继续生长氮掺杂梯度降低(x^-3)的SiC薄膜，并在SiC薄膜上蒸镀

肖特基接触电极，形成SiC同质结肖特基势垒变容二极管，对比无间隔层、无梯度掺杂SiC薄膜的平板型肖特基势垒变容二极管，前者的漏电流降低、损耗低、击穿电压提高、变容比率高、品质因子高、信号调幅范围大、动态负载调制范围宽、参数放大器的峰/均能量效率比更高。此论文与光敏型SiC异构结以及二维电子(空穴)气无关。Literature 14 [ASiC varactor with large effective tuning range for microwavepower applications, IEEE Electron Device Letters, Vol.32, No.6(2011):788-790.] Using Hot Wall Chemical Vapor Deposition (HWCVD) Technology on N ⁺ Type SiC A hydrogen-doped SiC spacer layer is first grown on the substrate, and then a SiC film with a reduced nitrogen doping gradient (x ^-3 ) is grown and evaporated on the SiC film

The Schottky contact electrode forms a SiC homojunction Schottky barrier varactor diode. Compared with the flat Schottky barrier varactor diode with no spacer layer and no gradient doped SiC film, the leakage current and loss of the former are reduced. Low, high breakdown voltage, high variable capacitance ratio, high quality factor, large signal amplitude modulation range, wide dynamic load modulation range, and higher peak/average energy efficiency ratio of parametric amplifiers. This paper has nothing to do with photosensitive SiC heterojunction and two-dimensional electron (hole) gas.

文献15[Design and large-signal characterization of high-Powervaractor-based impedance tuners,IEEE Transactions on Microwave Theory andTechniques,Vol.66,No.4(2018):1744-1753.]利用SiC变容二极管设计了2.2GHz大信号双短线阻抗调谐器，实验结果表明，得益于SiC变容二极管在高压、大功率方面的优势，双连续可调移相器不仅结构紧凑、简单，它在最大输入功率达到25W时插入损耗小于-2dB，反射系数小于0.8，相位失真低于5°。此论文只是同质结SiC变容二极管，与光敏型SiC异构结变容二极管以及二维电子(空穴)气无关。Literature 15 [Design and large-signal characterization of high-Powervaractor-based impedance tuners, IEEE Transactions on Microwave Theory and Techniques, Vol.66, No.4(2018):1744-1753.] designed a 2.2GHz varicap diode using SiC Large-signal double stub impedance tuner, the experimental results show that thanks to the advantages of SiC varactor diodes in high voltage and high power, the double continuous adjustable phase shifter is not only compact and simple, but it can be inserted when the maximum input power reaches 25W. The loss is less than -2dB, the reflection coefficient is less than 0.8, and the phase distortion is less than 5°. This paper is only a homojunction SiC varactor diode, and has nothing to do with photosensitive SiC heterojunction varactor diodes and two-dimensional electron (hole) gas.

文献16[一种指数掺杂的GaAs肖特基变容二极管及其制作方法，申请号201010132087X.]公开了一种指数掺杂的GaAs肖特基变容二极管，包括：半导体绝缘GaAs衬底、在衬底上外延生长的重掺杂的N⁺层、在N⁺层上外延生长的掺杂浓度呈指数分布的N型GaAs层、在N型GaAs层上蒸发肖特基接触的上电极、在N⁺层上蒸发金属形成欧姆接触的下电极；同时公开了该变容二极管的制作方法。可在不改变传统肖特基二极管结构的前提下，通过调节N型GaAs层的掺杂浓度，提高变容比，增强非线性，可用于周期性的非线性传输线中，能够提高毫米波、亚毫米波范围内倍频电路的工作频率和输出功率。此文献不涉及光敏型SiC异构结变容二极管以及二维电子(空穴)气。Document 16 [an exponentially doped GaAs Schottky varactor and its manufacturing method, application number 201010132087X.] discloses an exponentially doped GaAs Schottky varactor, including: a semiconductor insulating GaAs substrate, A heavily doped N ⁺ layer epitaxially grown on the substrate, an N-type GaAs layer with exponentially distributed doping concentration epitaxially grown on the N ⁺ layer, an upper electrode with Schottky contacts evaporated on the N-type GaAs layer, Metal is evaporated on the N ⁺ layer to form the lower electrode of the ohmic contact; meanwhile, a manufacturing method of the varactor diode is disclosed. Without changing the traditional Schottky diode structure, by adjusting the doping concentration of the N-type GaAs layer, the variable capacitance ratio can be improved, and the nonlinearity can be enhanced. It can be used in periodic nonlinear transmission lines, and can improve millimeter-wave, sub- Operating frequency and output power of frequency multiplier circuits in the millimeter wave range. This document does not deal with photosensitive SiC heterojunction varactors and two-dimensional electron (hole) gas.

文献17[高斯掺杂的砷化镓肖特基变容二极管及其制作方法，申请号2009103123924.]公开了一种高斯掺杂的GaAs肖特基变容二极管及其制作方法，包括半导体绝缘GaAs衬底、在衬底上部的高掺杂的N⁺型层、在N⁺型层上部的N型层、在N⁺型层上部生长的欧姆接触下电极和引线、在N型层上部生长的肖特基接触上电极和引线；同时提供了该变容二极管的制作方法。所提供的变容二极管结构灵活，易于应用在倍频电路中，变容比高、非线性强，有利于毫米波倍频电路输出功率的提高，高频特性好。此文献不涉及光敏型SiC异构结变容二极管以及二维电子(空穴)气。Document 17 [Gaussian doped gallium arsenide Schottky varactor diode and its manufacturing method, application number 2009103123924.] discloses a Gaussian doped GaAs Schottky varactor diode and its manufacturing method, including semiconductor insulating GaAs Substrate, highly doped N ⁺ type layer on top of substrate, N type layer on top of N ⁺ type layer, ohmic contact lower electrode and lead grown on top of N ⁺ type layer, The Schottky contacts the upper electrode and the lead wire; and a method for fabricating the varactor diode is also provided. The provided varactor diode has a flexible structure, is easy to be applied in a frequency doubling circuit, has a high varactor ratio and strong nonlinearity, is beneficial to the improvement of the output power of the millimeter wave frequency doubling circuit, and has good high-frequency characteristics. This document does not deal with photosensitive SiC heterojunction varactors and two-dimensional electron (hole) gas.

文献18[Formation of two-dimensional electron gases in polytypic SiChetero-structures electron gases in polytypic SiC hetero-structures,Journalof Applied Physics,Vol.98,No.5(2005):023709-1-7.]采用分子束外延(MBE)技术制备的半导体异质结3C/4H-SiC、3C/6H-SiC界面存在二维电子气(2DEG)，主要是由于界面的自发极化所致；3C/4H-SiC异质结界面2DEG的面密度高于AlGaN/GaN异质结界面2DEG的面密度，而且对势垒层厚度的变化不灵敏。此文献只涉及SiC异构结的二维电子(空穴)气，与光敏型变容二极管无关。Document 18 [Formation of two-dimensional electron gases in polytypic SiChetero-structures electron gases in polytypic SiC hetero-structures, Journal of Applied Physics, Vol.98, No.5(2005):023709-1-7.] adopts molecular beam epitaxy Two-dimensional electron gas (2DEG) exists at the interface of semiconductor heterojunction 3C/4H-SiC and 3C/6H-SiC prepared by (MBE) technology, mainly due to the spontaneous polarization of the interface; 3C/4H-SiC heterojunction The areal density of the interface 2DEG is higher than that of the AlGaN/GaN heterojunction interface, and it is not sensitive to the variation of the thickness of the barrier layer. This document only deals with the two-dimensional electron (hole) gas of SiC heterojunctions, and has nothing to do with photosensitive varactors.

文献19[Electron and hole confinement in hetero-crystalline SiCsuperlattice,Journal of the Physical Society of Japan,Vol.84,No.8(2015):084709-1-6.]分析认为，因为Si与C的电负性不同，电子从Si转移到C，将在六方相的SiC中引起自发极化，形成自发极化电荷；但因为对称性高，立方相的SiC没有自发极化。另一方面，因为3C-SiC的带隙E_g＝2.39eV，4H-SiC的带隙E_g＝3.26eV，6H-SiC的带隙E_g＝3.02eV，3C/4H-SiC、3C/6H-SiC的导带带阶ΔE_c接近1eV，室温环境下3C/4H-SiC、3C/6H-SiC异构结的界面势阱中储存了高密度的二维电子气(2DEG)、二维空穴气(2DHG)，非常适用于高电子迁移率晶体管(HEMT)。此论文只涉及SiC异构结超晶格的二维电子(空穴)气，但还没有异构结势垒变容二极管(HBV)等相关器件的研究报道，与光敏型变容二极管无关。Literature 19 [Electron and hole confinement in hetero-crystalline SiC superlattice, Journal of the Physical Society of Japan, Vol.84, No.8(2015):084709-1-6.] analyzed that because of the electronegativity of Si and C Differently, the transfer of electrons from Si to C will cause spontaneous polarization in the hexagonal SiC, forming a spontaneous polarization charge; but because of the high symmetry, the cubic SiC has no spontaneous polarization. On the other hand, since the band gap of 3C-SiC is E _g = 2.39 eV, the band gap of 4H-SiC is E _g = 3.26 eV, the band gap of 6H-SiC is E _g = 3.02 eV, 3C/4H-SiC, 3C/6H -The conduction band order ΔE _c of SiC is close to 1eV, and high-density two-dimensional electron gas (2DEG) and two-dimensional empty space are stored in the interfacial potential wells of 3C/4H-SiC and 3C/6H-SiC heterojunctions at room temperature. Cavitation gas (2DHG), ideal for high electron mobility transistors (HEMTs). This paper only involves the two-dimensional electron (hole) gas of SiC heterojunction superlattice, but there is no research report on related devices such as heterojunction barrier varactors (HBV), which has nothing to do with photosensitive varactors.

通过分析、归纳现有异质结势垒变容二极管的相关文献，没有发现与本发明的光敏型SiC异构结多势垒变容二极管相同、相似，或者对本发明有启发的技术方案。By analyzing and summarizing the relevant documents of the existing heterojunction barrier varactors, no technical solutions that are the same or similar to the photosensitive SiC heterojunction multi-barrier varactors of the present invention, or are inspiring to the present invention are found.

发明内容SUMMARY OF THE INVENTION

本发明的目的是为了克服现有技术存在的缺点和不足，而提供一种光敏型SiC异构结多势垒变容二极管，该方案创新机理新颖、由立方相碳化硅(3C-SiC)与六方相碳化硅(4H-SiC、6H-SiC)构成的异构结多势垒变容二极管，具有电容小、耐压高，适用于倍频、电调谐、参数放大、光探测等相关领域。The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, and provide a photosensitive SiC heterogeneous junction multi-barrier varactor diode, which has a novel innovation mechanism and is composed of cubic phase silicon carbide (3C-SiC) and Heterogeneous junction multi-barrier varactor diodes composed of hexagonal silicon carbide (4H-SiC, 6H-SiC) have small capacitance and high withstand voltage, and are suitable for frequency doubling, electrical tuning, parameter amplification, optical detection and other related fields.

为实现上述目的，本发明的技术方案是包括依次设置的N⁺型3C-SiC衬底、至少一组异构结、N⁺型3C-SiC接触层；In order to achieve the above object, the technical solution of the present invention is to include N ⁺ type 3C-SiC substrates, at least one group of heterogeneous junctions, and N ⁺ type 3C-SiC contact layers arranged in sequence;

所述异构结由N型3C-SiC调制层、本征4H-SiC或者6H-SiC势垒层、N型3C-SiC调制层构成，所述异构结中，窄带隙的N型3C-SiC为势阱，宽带隙的本征4H-SiC或本征6H-SiC为势垒；The heterogeneous junction is composed of an N-type 3C-SiC modulation layer, an intrinsic 4H-SiC or 6H-SiC barrier layer, and an N-type 3C-SiC modulation layer. SiC is the potential well, and the intrinsic 4H-SiC or intrinsic 6H-SiC with wide bandgap is the potential barrier;

所述异构结表面产生二氧化硅保护层，之外涂覆遮光层；A silica protective layer is produced on the surface of the isomer junction, and a light-shielding layer is coated externally;

所述的N⁺型3C-SiC衬底、N⁺型3C-SiC接触层的外表面分别有欧姆电极；The outer surfaces of the N ⁺ type 3C-SiC substrate and the N ⁺ type 3C-SiC contact layer are respectively provided with ohmic electrodes;

N⁺型3C-SiC接触层的外表面上设置有用于光敏驱动的透光孔。The outer surface of the N ⁺ type 3C-SiC contact layer is provided with light-transmitting holes for photosensitive driving.

进一步设置是所述N⁺型3C-SiC衬底的载流子浓度范围1.0×10²⁴—9.0×10²⁵米^-3，厚度范围2.0—3.0×10^-4米，所述N⁺型3C-SiC衬底的掺杂为磷掺杂。Further settings are that the carrier concentration range of the N ⁺ type 3C-SiC substrate is 1.0×10 ²⁴ -9.0×10 ²⁵ m ^-3 , and the thickness range is 2.0-3.0×10 ^-4 m, and the N ⁺ type 3C- The doping of the SiC substrate is phosphorus doping.

进一步设置是所述N型3C-SiC调制层表面是硅原子面、碳原子面其中之一，调制层的表面是正轴、偏轴其中之一；所述N型3C-SiC调制层的载流子浓度范围1.0×10²²—9.0×10²³米^-3，厚度为范围1.0×10^-8—9.0×10^-7米，所述N型3C-SiC调制层的掺杂为磷掺杂。It is further set that the surface of the N-type 3C-SiC modulation layer is one of a silicon atomic plane and a carbon atomic plane, and the surface of the modulation layer is one of a positive axis and an off-axis; the current carrying of the N-type 3C-SiC modulation layer is The sub-concentration ranges from 1.0×10 ²² to 9.0×10 ²³ m ⁻³ , the thickness ranges from 1.0×10 ⁻⁸ to 9.0×10 ⁻⁷ m, and the N-type 3C-SiC modulation layer is doped with phosphorus.

进一步设置是所述的本征4H-SiC势垒层或本征6H-SiC势垒层厚度范围1.0—9.0×10^-8m，且不掺杂。Further settings are that the intrinsic 4H-SiC barrier layer or the intrinsic 6H-SiC barrier layer has a thickness in the range of 1.0-9.0×10 ^-8 m, and is not doped.

进一步设置是所述的N型3C-SiC调制层载流子浓度范围1.0×10²²—9.0×10²³米^-3，厚度范围1.0×10^-8—9.0×10^-7米，所述的N型3C-SiC调制层的掺杂为磷掺杂。Further settings are that the carrier concentration range of the N-type 3C-SiC modulation layer is 1.0×10 ²² -9.0×10 ²³ m ^-3 , the thickness range is 1.0×10 ^-8 -9.0×10 ^-7 m, the N The doping of the type 3C-SiC modulation layer is phosphorus doping.

进一步设置是所述的异构结的周期数根据耐压和容量需要设置，该周期数为2—20个。The further setting is that the number of cycles of the heterogeneous junction is set according to the needs of pressure resistance and capacity, and the number of cycles is 2-20.

进一步设置是所述的N⁺型3C-SiC接触层载流子浓度范围1.0×10²⁴—9.0×10²⁵，厚度范围1.0—5.0×10^-7米，该N⁺型3C-SiC接触层为磷掺杂。It is further set that the carrier concentration range of the N ⁺ type 3C-SiC contact layer is 1.0×10 ²⁴ —9.0×10 ²⁵ and the thickness is in the range of 1.0 — 5.0×10 ^-7 meters, and the N ⁺ type 3C-SiC contact layer is Phosphorus doping.

进一步设置是所述的电极为电子束蒸发技术蒸镀形成的金镍电极。It is further provided that the electrodes are gold-nickel electrodes formed by electron beam evaporation technology.

进一步设置是所述N⁺型3C-SiC接触层的表面中部刻出透光孔，此通光孔面积范围是异构结横截面积的1/3-1/2。A further arrangement is that a light-transmitting hole is carved in the middle of the surface of the N ⁺ type 3C-SiC contact layer, and the area of the light-transmitting hole is 1/3-1/2 of the cross-sectional area of the heterogeneous junction.

进一步设置是所述异构结表面产生二氧化硅保护层，采用热氧化工艺，对整个异构结的表面进行氧化，产生二氧化硅保护层；所述之外涂覆遮光层，采用不透光、不导电、耐腐蚀的树脂制造。It is further set that a silica protective layer is formed on the surface of the isomer junction, and a thermal oxidation process is used to oxidize the entire surface of the isomer junction to generate a silica protective layer; Manufactured from light, non-conductive, corrosion-resistant resin.

本发明的二极管，其中所包含的多个异构结势垒电容器串联起来，整个变容二极管的等效电容小于单个异构结势垒电容器的电容，而整个变容二极管的端电压大于单个异构结势垒电容器的电压。即，本发明的异构结多势垒变容二极管的电容小、耐压高，适用于高频、大功率领域。另外，采用波长合适的光(如绿光)照射该异构结，因为3C-SiC的禁带宽度(Eg)与绿光能量相当，3C-SiC调制层吸收绿光转换成光生载流子，储存在窄带隙的3C-SiC势阱之中；4H-SiC、6H-SiC的禁带宽度值大于绿光的能量值，不吸收绿光，没有光生载流子。由于吸收光的势阱中载流子增多，因此光照区域形成的异构结势垒电容器的电容增大；没有光照区域的势阱中载流子不变，因此无光照区域形成的势垒电容器的电容不变。两部分区域的电容器并联，因此光照后的电容变大，耐压不变。即本发明的3C/4H-SiC、3C/6H-SiC异构结多势垒变容二极管作为一种新型微波光电子器件，可用于倍频、电调谐、参数放大、光探测等。In the diode of the present invention, the plurality of heterogeneous junction barrier capacitors contained therein are connected in series, the equivalent capacitance of the entire varactor diode is smaller than that of a single heterogeneous junction barrier capacitor, and the terminal voltage of the entire varactor diode is greater than that of a single heterogeneous junction barrier capacitor. Structural barrier capacitor voltage. That is, the heterogeneous junction multi-barrier varactor diode of the present invention has small capacitance and high withstand voltage, and is suitable for high-frequency and high-power fields. In addition, the heterojunction is irradiated with light of suitable wavelength (such as green light), because the forbidden band width (Eg) of 3C-SiC is equivalent to the energy of green light, and the 3C-SiC modulation layer absorbs green light and converts it into photogenerated carriers, It is stored in the 3C-SiC potential well with a narrow band gap; the value of the forbidden band width of 4H-SiC and 6H-SiC is greater than the energy value of green light, which does not absorb green light and has no photogenerated carriers. Due to the increase of carriers in the potential well that absorbs light, the capacitance of the heterogeneous junction barrier capacitor formed in the illuminated area increases; the carriers in the potential well in the unilluminated area remain unchanged, so the barrier capacitor formed in the unilluminated area capacitance does not change. The capacitors in the two parts are connected in parallel, so the capacitance after illumination becomes larger and the withstand voltage remains unchanged. That is, the 3C/4H-SiC, 3C/6H-SiC heterogeneous junction multi-barrier varactor diode of the present invention, as a new type of microwave optoelectronic device, can be used for frequency doubling, electrical tuning, parameter amplification, light detection and the like.

实施本发明的有益效果Implementing the beneficial effects of the present invention

本发明提出的光敏型SiC异构结多势垒变容二极管，具有电容-电压关系关于0电压对称且电流-电压关系关于0电压奇对称、电容小、耐压高、变容比率高、截止频率高、动态负载调制范围宽、光照调节电容等特点。用于奇次谐波倍增时无需偶次谐波的空载电路，电路设计简化；可以利用SiC异构结的二维电子(空穴)气调节电容，扩展偏置电压范围，改善电容——电压关系，提高载波——奇次谐波的转换效率；光电容式探测器具有更高的灵敏度。本发明的光敏型SiC异构结多势垒变容二极管适用于倍频、电调谐、参数放大、光探测等，等等。本发明不仅提供单个器件，也为光电集成电路提供设计思路。The photosensitive SiC heterogeneous junction multi-barrier varactor diode proposed by the present invention has a capacitance-voltage relationship that is symmetric about 0 voltage and a current-voltage relationship that is oddly symmetric about 0 voltage, small capacitance, high withstand voltage, high variable capacitance ratio, and cut-off. It has the characteristics of high frequency, wide dynamic load modulation range, light adjustment capacitor and so on. It is used for no-load circuits that do not require even harmonics when multiplying odd harmonics, and the circuit design is simplified; the two-dimensional electron (hole) gas of SiC heterogeneous junction can be used to adjust capacitance, expand the range of bias voltage, and improve capacitance—— The voltage relationship improves the conversion efficiency of carrier-odd harmonics; the photocapacitive detector has higher sensitivity. The photosensitive SiC heterogeneous junction multi-barrier varactor diode of the present invention is suitable for frequency doubling, electrical tuning, parameter amplification, light detection, and the like. The present invention not only provides a single device, but also provides a design idea for an optoelectronic integrated circuit.

附图说明Description of drawings

为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，根据这些附图获得其他的附图仍属于本发明的范畴。In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention, and for those of ordinary skill in the art, obtaining other drawings according to these drawings still belongs to the scope of the present invention without any creative effort.

图1是本发明实施例一提供的光敏型碳化硅异构结多势垒变容二极管的示意图，其中(a)是3C/4H-SiC异构结的多势垒变容二极管，(b)是3C/6H-SiC异构结的多势垒变容二极管；1 is a schematic diagram of a photosensitive silicon carbide heterogeneous junction multi-barrier varactor diode provided in Embodiment 1 of the present invention, wherein (a) is a 3C/4H-SiC heterogeneous junction multi-barrier varactor diode, (b) It is a multi-barrier varactor diode of 3C/6H-SiC heterojunction;

图2为本发明实施例一提供的光敏型碳化硅异构结多势垒变容二极管中的能带、等效电容器示意图，其中(a)是3C/4H-SiC异构结的，(b)是3C/6H-SiC异构结的；2 is a schematic diagram of the energy band and equivalent capacitor in the photosensitive silicon carbide heterojunction multi-barrier varactor diode provided in the first embodiment of the present invention, wherein (a) is a 3C/4H-SiC heterojunction, (b) ) is 3C/6H-SiC heterojunction;

图3是本发明实施例一提供的光敏型碳化硅异构结多势垒变容二极管，相当于：无光照时就是一个电容器，有光照时，光照区域的中部变容二极管与无光照区域的边沿变容二极管二者并联；3 is a photosensitive silicon carbide heterogeneous junction multi-barrier varactor diode provided in the first embodiment of the present invention, which is equivalent to a capacitor when there is no light. The edge varactor diodes are connected in parallel;

图4为本发明实施例一提供的包含2、4个周期(N)3C/4H/(N)3C-SiC异构结的光敏型碳化硅异构结多势垒变容二极管在室温下有、无光照时电容—电压关系模拟图；FIG. 4 shows the photosensitive silicon carbide heterojunction multi-barrier varactor diode including 2 or 4 cycles of (N)3C/4H/(N)3C-SiC heterojunction provided by the first embodiment of the present invention. , Capacitance-voltage relationship simulation diagram when there is no light;

图5为本发明实施例一提供的包含2、4个周期(N)3C/4H/(N)3C-SiC异构结的光敏型碳化硅异构结多势垒变容二极管在室温下有、无光照时电流—电压关系模拟图。FIG. 5 shows the photosensitive silicon carbide heterojunction multi-barrier varactor diode including 2 or 4 cycles of (N)3C/4H/(N)3C-SiC heterojunction provided by the first embodiment of the present invention. , The simulation diagram of the current-voltage relationship when there is no light.

具体实施方式Detailed ways

为使本发明的目的、技术方案和优点更加清楚，下面将结合附图对本发明作进一步地详细描述。In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

实施例一Example 1

本发明实施例一提供一种结构如说明书附图1(a)所示的电极/N⁺型3C-SiC/N型3C-SiC/本征4H-SiC/N型3C-SiC/N⁺型3C-SiC/电极——光敏型SiC异构结多势垒变容二极管，包括以下步骤：The first embodiment of the present invention provides an electrode/N ⁺ type 3C-SiC/N type 3C-SiC/intrinsic 4H-SiC/N type 3C-SiC/N ⁺ type structure as shown in FIG. 1(a) of the specification 3C-SiC/electrode - photosensitive SiC heterogeneous junction multi-barrier varactor, including the following steps:

A1，选择N⁺型3C-SiC衬底，载流子浓度范围1.0×10²⁴—9.0×10²⁵米^-3，厚度约为2.0×10^-4米，所述N⁺型3C-SiC衬底的掺杂为磷掺杂。A1, select N ⁺ type 3C-SiC substrate, the carrier concentration range is 1.0×10 ²⁴ —9.0×10 ²⁵ m ^-3 , and the thickness is about 2.0×10 ^-4 m, the N ⁺ type 3C-SiC substrate The doping is phosphorus doping.

A2，在N⁺型3C-SiC衬底上生长N型3C-SiC调制层，调制层表面可以是Si原子面、C原子面之中其一，调制层的表面可以是正轴、偏轴之中其一；调制层的载流子浓度范围1.0×10²²—9.0×10²³米^-3，厚度范围1.0×10^-8—9.0×10^-7米，调制层的掺杂为磷掺杂，可以采用分子束外延(MBE)、金属有机物化学气相沉积(MOCVD)技术之中其一生长。A2, grow an N-type 3C-SiC modulation layer on an N ⁺ -type 3C-SiC substrate, the surface of the modulation layer can be one of Si atomic plane and C atomic plane, and the surface of the modulation layer can be between the positive axis and the off-axis First, the carrier concentration of the modulation layer ranges from 1.0×10 ²² to 9.0×10 ²³ m ^-3 , the thickness ranges from 1.0×10 ^-8 to 9.0×10 ^-7 m, and the modulation layer is doped with phosphorus, which can be It is grown by one of molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD) techniques.

A3，在N型3C-SiC调制层上生长本征4H-SiC势垒层，厚度范围1.0—9.0×10^-8m，所述本征4H-SiC势垒层不掺杂，可以采用MBE、MOCVD方法之中其一生长。A3, grow an intrinsic 4H-SiC barrier layer on the N-type 3C-SiC modulation layer with a thickness ranging from 1.0 to 9.0×10 ^-8 m. The intrinsic 4H-SiC barrier layer is not doped. MBE, One of the MOCVD methods to grow.

A4，在本征4H-SiC势垒层上生长N型3C-SiC调制层，调制层载流子浓度范围1.0×10²²—9.0×10²³米^-3，厚度范围1.0×10^-8—9.0×10^-7米，N型3C-SiC调制层的掺杂为磷掺杂，可以采用MBE、MOCVD方法之中其一生长。A4, N-type 3C-SiC modulation layer is grown on the intrinsic 4H-SiC barrier layer, the carrier concentration of the modulation layer is 1.0×10 ²² —9.0×10 ²³ m ^-3 , and the thickness is 1.0×10 ^-8 —9.0 ×10 ^-7 m, the N-type 3C-SiC modulation layer is doped with phosphorus, and can be grown by either MBE or MOCVD.

A5，根据耐压和容量需要，决定本征N型3C-SiC/4H-SiC/N型3C-SiC异构结的周期，可以是2—20个。A5, according to the requirements of withstand voltage and capacity, determine the period of the intrinsic N-type 3C-SiC/4H-SiC/N-type 3C-SiC heterojunction, which can be 2-20.

A6，再沉积N⁺型3C-SiC接触层，载流子浓度范围1.0×10²⁴—9.0×10²⁵米^-3，厚度范围1.0—5.0×10^-7米，所述再沉积N⁺型3C-SiC接触层的掺杂为磷掺杂，N⁺型3C-SiC接触层与电极形成欧姆接触；N⁺型3C-SiC接触层可以采用MBE、MOCVD方法之中其一生长。A6, redeposited N ⁺ type 3C-SiC contact layer, the carrier concentration range is 1.0×10 ²⁴ —9.0×10 ²⁵ m ^-3 , and the thickness is in the range of 1.0—5.0×10 ^-7 m, the redeposited N ⁺ type 3C The -SiC contact layer is doped with phosphorus, and the N ⁺ type 3C-SiC contact layer forms an ohmic contact with the electrode; the N ⁺ type 3C-SiC contact layer can be grown by one of MBE and MOCVD methods.

A7，采用热氧化工艺，对整个异构结的表面进行氧化，产生二氧化硅保护层。A7, using a thermal oxidation process to oxidize the entire surface of the isomer junction to produce a silicon dioxide protective layer.

A8，在整个异构结表面的二氧化硅保护层上涂覆不透光、不导电、耐腐蚀的树脂遮光层。A8, coat the opaque, non-conductive, corrosion-resistant resin light-shielding layer on the silica protective layer on the entire surface of the isomer junction.

A9，在N⁺型3C-SiC衬底、接触层的上表面分别蒸镀金镍电极，首先刻蚀N⁺型3C-SiC衬底、接触层上表面的二氧化硅保护层；在N⁺型3C-SiC衬底、接触层的上表面分别蒸镀金镍合金电极，分别欧姆连接于所述N⁺型3C-SiC衬底、接触层；所述金镍合金电极，可以选用金镍合金作为原料，采用电子束蒸发技术生长。A9, respectively evaporate gold-nickel electrodes on the upper surfaces of the N ⁺ type 3C-SiC substrate and the contact layer, first etch the N ⁺ type 3C-SiC substrate ^and the silicon dioxide protective layer on the upper surface of the contact layer; Gold-nickel alloy electrodes are vapor-deposited on the upper surfaces of the 3C-SiC substrate and the contact layer, respectively, and are respectively ohmically connected to the N ⁺ type 3C-SiC substrate and the contact layer; the gold-nickel alloy electrodes can be selected from gold-nickel alloys as raw materials. , grown by electron beam evaporation technique.

A10，采用腐蚀液，先腐蚀掉接触层金镍电极上面的遮光层，再腐蚀掉接触层上金镍电极的中部，刻出面积范围是异构结横截面积的1/3—1/2的通光孔。A10, use etching solution to first etch the light-shielding layer on the gold-nickel electrode of the contact layer, and then etch the middle of the gold-nickel electrode on the contact layer, and the engraved area is 1/3-1/2 of the cross-sectional area of the heterogeneous junction of the light hole.

完成上述十个步骤，制成金镍欧姆电极/N⁺型3C-SiC/N型3C-SiC/4H-SiC/N型3C-SiC/N⁺型3C-SiC/金镍欧姆电极——光敏型SiC异构结多势垒变容二极管。Complete the above ten steps to make gold-nickel ohmic electrode/N ⁺ type 3C-SiC/N-type 3C-SiC/4H-SiC/N-type 3C-SiC/N ⁺ -type 3C-SiC/gold-nickel ohmic electrode - photosensitive SiC heterojunction multi-barrier varactor diodes.

实施例二Embodiment 2

本发明实施例二提供一种结构如说明书附图1(b)所示的电极/N⁺型3C-SiC/N型3C-SiC/本征6H-SiC/N型3C-SiC/N⁺型3C-SiC/电极——光敏型SiC异构结多势垒变容二极管，包括以下步骤：The second embodiment of the present invention provides an electrode/N ⁺ type 3C-SiC/N type 3C-SiC/intrinsic 6H-SiC/N type 3C-SiC/N ⁺ type structure as shown in FIG. 1(b) of the specification 3C-SiC/electrode - photosensitive SiC heterogeneous junction multi-barrier varactor, including the following steps:

B1，选择N⁺型3C-SiC衬底，载流子浓度范围1.0×10²⁴—9.0×10²⁵米^-3，厚度约为2.0×10^-4米，所述N⁺型3C-SiC衬底的掺杂为磷掺杂。B1, select N ⁺ type 3C-SiC substrate, the carrier concentration range is 1.0×10 ²⁴ —9.0×10 ²⁵ m ^-3 , and the thickness is about 2.0×10 ^-4 m, the N ⁺ type 3C-SiC substrate The doping is phosphorus doping.

B2，在N⁺型3C-SiC衬底上生长N型3C-SiC调制层，调制层表面可以是Si原子面、C原子面之中其一，调制层的表面可以是正轴、偏轴之中其一；调制层的载流子浓度范围1.0×10²²—9.0×10²³米^-3，厚度范围1.0×10^-8—9.0×10^-7米，调制层的掺杂为磷掺杂，可以采用MBE、MOCVD方法之中其一生长。B2, grow the N-type 3C-SiC modulation layer on the N ⁺ type 3C-SiC substrate, the surface of the modulation layer can be one of Si atomic plane and C atomic plane, and the surface of the modulation layer can be between the positive axis and the off-axis First, the carrier concentration of the modulation layer ranges from 1.0×10 ²² to 9.0×10 ²³ m ^-3 , the thickness ranges from 1.0×10 ^-8 to 9.0×10 ^-7 m, and the modulation layer is doped with phosphorus, which can be It is grown by one of MBE and MOCVD methods.

B3，在N型3C-SiC调制层上生长本征6H-SiC势垒层，厚度范围1.0—9.0×10^-8m，本征6H-SiC势垒层不掺杂，可以采用MBE、MOCVD方法之中其一生长。B3, grow the intrinsic 6H-SiC barrier layer on the N-type 3C-SiC modulation layer, the thickness range is 1.0-9.0×10 ^-8 m, the intrinsic 6H-SiC barrier layer is not doped, MBE and MOCVD methods can be used One of them grows.

B4，在本征6H-SiC势垒层上生长N型3C-SiC调制层，调制层载流子浓度范围1.0×10²²—9.0×10²³米^-3，厚度范围1.0×10^-8—9.0×10^-7米，N型3C-SiC调制层的掺杂为磷掺杂，可以采用MBE、MOCVD方法之中其一生长。B4, N-type 3C-SiC modulation layer is grown on the intrinsic 6H-SiC barrier layer, the carrier concentration of the modulation layer is 1.0×10 ²² —9.0×10 ²³ m ^-3 , and the thickness is 1.0×10 ^-8 —9.0 ×10 ^-7 m, the N-type 3C-SiC modulation layer is doped with phosphorus, and can be grown by either MBE or MOCVD.

B5，根据耐压和容量需要，决定本征6H-SiC/N型3C-SiC异构结的周期，可以是2—20个。B5, according to the requirements of withstand voltage and capacity, determine the period of the intrinsic 6H-SiC/N-type 3C-SiC heterojunction, which can be 2-20.

B6，再沉积N⁺型3C-SiC接触层，载流子浓度范围1.0×10²⁴—9.0×10²⁵米^-3，厚度范围1.0—5.0×10^-7米，所述再沉积N⁺型3C-SiC接触层的掺杂为磷掺杂，N⁺型3C-SiC接触层与电极形成欧姆接触；N⁺型3C-SiC接触层可以采用MBE、MOCVD方法之中其一生长。B6, redeposited N ⁺ type 3C-SiC contact layer, the carrier concentration range is 1.0×10 ²⁴ —9.0×10 ²⁵ m ^-3 , and the thickness is in the range of 1.0—5.0×10 ^-7 m, the redeposited N ⁺ type 3C The -SiC contact layer is doped with phosphorus, and the N ⁺ type 3C-SiC contact layer forms an ohmic contact with the electrode; the N ⁺ type 3C-SiC contact layer can be grown by one of MBE and MOCVD methods.

B7，采用热氧化工艺，对整个异构结的表面进行氧化，产生二氧化硅保护层。In B7, a thermal oxidation process is used to oxidize the entire surface of the isomer junction to produce a silicon dioxide protective layer.

B8，在整个异构结表面的二氧化硅保护层上涂覆不透光、不导电、耐腐蚀的树脂遮光层。B8, coat the opaque, non-conductive, corrosion-resistant resin light-shielding layer on the silica protective layer on the entire surface of the isomer junction.

B9，在N⁺型3C碳化硅衬底、接触层的上表面分别蒸镀金镍电极，首先刻蚀N⁺型3C碳化硅衬底、接触层上表面的二氧化硅保护层；在N⁺型3C碳化硅衬底、接触层的上表面分别蒸镀金镍合金电极，分别欧姆连接于所述N⁺型3C碳化硅衬底、接触层；所述金镍合金电极，可以选用金镍合金作为原料，采用电子束蒸发技术生长。B9, respectively vapor-deposit gold-nickel electrodes on the upper surfaces of the N ⁺ type 3C silicon carbide substrate and the contact layer, first etch the N ⁺ type 3C silicon carbide substrate ^and the silicon dioxide protective layer on the upper surface of the contact layer; Gold-nickel alloy electrodes are vapor-deposited on the upper surfaces of the 3C silicon carbide substrate and the contact layer, respectively, and are respectively ohmically connected to the N ⁺ type 3C silicon carbide substrate and the contact layer; the gold-nickel alloy electrodes can be selected from gold-nickel alloys as raw materials. , grown by electron beam evaporation technique.

B10，采用腐蚀液，先腐蚀掉接触层金镍电极上面的遮光层，再腐蚀掉接触层上金镍电极的中部，刻出面积范围是异构结横截面积的1/3—1/2的通光孔。B10, using etching solution, first etch the light-shielding layer above the gold-nickel electrode of the contact layer, and then etch the middle of the gold-nickel electrode on the contact layer, and the engraved area is 1/3-1/2 of the cross-sectional area of the heterogeneous junction of the light hole.

完成上述十个步骤，制成金镍欧姆电极/N⁺型3C-SiC/N型3C-SiC/6H-SiC/N型3C-SiC/N⁺型3C-SiC/金镍欧姆电极——光敏型SiC异构结多势垒变容二极管。Complete the above ten steps to make gold-nickel ohmic electrode/N ⁺ type 3C-SiC/N-type 3C-SiC/6H-SiC/N-type 3C-SiC/N ⁺ -type 3C-SiC/gold-nickel ohmic electrode - photosensitive SiC heterojunction multi-barrier varactor diodes.

在本发明实施例一对光敏型SiC异构结多势垒变容二极管建模和模拟时，电极/N⁺型3C-SiC/N型3C-SiC/本征4H-SiC/N型3C-SiC/N⁺型3C-SiC/电极——结构如说明书附图1(a)所示。描述光敏型SiC异构结多势垒变容二极管的半导体器件基本方程(泊松方程、电流密度方程、连续性方程)中，除了载流子(电子、空穴)的漂移、扩散机制之外，还应该计入异构结多势垒变容二极管中3C/4H-SiC异构结界面自发极化效应，以及光生载流子效应。When modeling and simulating a pair of photosensitive SiC heterogeneous junction multi-barrier varactor diodes in the embodiment of the present invention, the electrode/N ⁺ type 3C-SiC/N type 3C-SiC/intrinsic 4H-SiC/N type 3C- SiC/N ⁺ type 3C-SiC/electrode - the structure is shown in Figure 1(a) of the specification. In the basic equations (Poisson equation, current density equation, continuity equation) of semiconductor devices describing photosensitive SiC heterojunction multi-barrier varactors, except for the drift and diffusion mechanisms of carriers (electrons, holes) , the spontaneous polarization effect of the 3C/4H-SiC heterojunction interface in the heterojunction multi-barrier varactor, and the photogenerated carrier effect should also be taken into account.

本发明具体实施例一光敏型SiC异构结多势垒变容二极管中载流子(电子、空穴)传导应当遵守的泊松方程列为式(1)：Specific embodiment of the present invention one photosensitive SiC heterogeneous junction multi-barrier varactor The carrier (electron, hole) conduction that should be obeyed by the Poisson equation is listed as formula (1):

式中E(x)为电场，N(x)、P(x)分别为电子浓度和空穴浓度，ε是介电常数，q＝1.6×10^-19库伦是基本电荷，N_D、N_A是掺杂杂质的浓度，П(x)是电极化强度。因为本发明实施例一只涉及3C/4H-SiC异构结，虽然六方相的4H-SiC包含了自发极化和压电极化，但立方相的3C-SiC因为其对称性更高，只有自发极化；还因为3C/4H-SiC异构结的界面失配不到0.1％，界面失配引起的压电极化忽略不计，(1)式中的P(x)只包含自发极化。对于同质结或者没有界面极化的异质结、异构结，П(x)＝0。where E(x) is the electric field, N(x) and P(x) are the electron concentration and hole concentration, respectively, ε is the dielectric constant, q=1.6×10 ^-19 Coulomb is the basic charge, N _D , N _A is the concentration of doping impurities, and П(x) is the electrical polarization. Because the embodiment of the present invention only involves the 3C/4H-SiC heterojunction, although the hexagonal 4H-SiC contains spontaneous polarization and piezoelectric polarization, the cubic 3C-SiC has higher symmetry and only Spontaneous polarization; also because the interface mismatch of the 3C/4H-SiC heterojunction is less than 0.1%, the piezoelectric polarization caused by the interface mismatch is negligible, and P(x) in equation (1) only includes the spontaneous polarization . For homojunction or heterojunction and heterojunction without interface polarization, П(x)=0.

为此，需要自适应求解泊松方程和薛定额方程，才能得到光敏型碳化硅异构结多势垒变容二极管中3C/4H-SiC异构结界面的自由电荷总量，即二维电子气(2DEG)的密度[n₂(x)]与三维电子密度[n₃(x)]的总和。泊松方程已列为式(1)，薛定额方程列为式(2)，For this reason, it is necessary to solve the Poisson equation and Schröding equation adaptively to obtain the total amount of free charges at the interface of the 3C/4H-SiC heterogeneous junction in the photosensitive SiC heterogeneous junction multi-barrier varactor, that is, the two-dimensional electron The sum of the density of gas (2DEG) [n ₂ (x)] and the three-dimensional electron density [n ₃ (x)]. Poisson equation has been listed as formula (1), Schrodinger equation is listed as formula (2),

式中

为约化普朗克常数，m_∥ ^*(x)为垂直结方向(x)上与位置相关的电子有效质量，V(x)是电子势能即导带边，i是量子化能级的序数，F_i是第i个量子化能级的能量，Ψ_i是波函数。本发明具体实施例一光敏型SiC异构结多势垒变容二极管中二维电子气(2DEG)的密度[n₂(x)]列为式(3)，in the formula

In order to reduce Planck's constant, m _∥ ^* (x) is the position-dependent effective mass of the electron in the vertical junction direction (x), V(x) is the electron potential energy, that is, the conduction band edge, and i is the ordinal number of the quantized energy level , F _i is the energy of the i-th quantized energy level, and Ψ _i is the wave function. The density [n ₂ (x)] of the two-dimensional electron gas (2DEG) in the photosensitive SiC heterogeneous junction multi-barrier varactor diode in the specific embodiment of the present invention is listed in the formula (3),

式中k为玻尔兹曼常数，m_⊥ ^*(x)为垂直x方向上位置相关的电子有效质量，v是等价导带最小值的数量，E_F是费米能级的能量，E_sep是分离能，T是热力学温度。本发明具体实施例一光敏型SiC异构结多势垒变容二极管中异构结的三维电子的密度[n₃(x)]列为式(4)，where k is the Boltzmann constant, m _⊥ ^* (x) is the position-dependent effective mass of the electron in the vertical x direction, v is the number of equivalent conduction band minima, E _F is the energy of the Fermi level, E _sep is the separation energy and T is the thermodynamic temperature. The density [n ₃ (x)] of the three-dimensional electrons of the heterojunction in the photosensitive SiC heterojunction multi-barrier varactor diode in the specific embodiment of the present invention is listed in the formula (4),

n₃(x)＝N_cf₁₂(η,b), (4)n ₃ (x)=N _c f ₁₂ (η,b), (4)

式中N_c是导带的三维有效态密度，f_1/2(η,b)是不完全费米积分。where N _c is the three-dimensional effective density of states of the conduction band, and f _1/2 (η, b) is the incomplete Fermi integral.

本发明具体实施例一光敏型SiC异构结多势垒变容二极管中载流子传导应当遵守的电子电流密度(J_n)、空穴电流密度(J_p)方程分别列为式(5)和(6)，The specific embodiment of the present invention 1 The electron current density (J _n ) and hole current density (J _p ) equations that should be obeyed by the carrier conduction in the photosensitive SiC heterogeneous junction multi-barrier varactor diode are respectively listed as formula (5) and (6),

式中v_n、v_p分别是电子、空穴的漂移速度，μ_n、μ_p分别是电子、空穴的迁移率，D_n、D_p分别是电子、空穴的扩散系数。式(5)和式(6)中等号右边的第一项是漂移电流部分，第二项是扩散电流部分，第三项是与电子、空穴密度梯度引起的波姆势H_n、H_p相关的电流密度，第四项是光生电子、空穴电流密度。电子、空穴的波姆势H_n、H_p分别列为式(7)和(8)：where v _n and v _p are the drift velocities of electrons and holes, respectively, μ _n and μ _p are the mobility of electrons and holes, respectively, and D _n and D _p are the diffusion coefficients of electrons and holes, respectively. The first term on the right side of the equation (5) and (6) is the drift current part, the second term is the diffusion current part, and the third term is the Bomb potential H _n , H _p caused by the electron and hole density gradients The relevant current density, the fourth term is the photogenerated electron and hole current density. The Bohm potentials H _n and H _p of electrons and holes are listed as formulas (7) and (8), respectively:

式中系数s_p、s_n为材料系数，

r_p(n)为具有统计意义的无量纲量，针对适合高温工作的SiC半导体器件，r_p、r_n取3。In the formula, the coefficients s _p and s _n are the material coefficients,

_{r p (n)} is a dimensionless quantity with statistical significance. For SiC semiconductor devices suitable for high temperature operation, rp and rn are taken as 3.

光照引起的光生电子、空穴电流密度可按如下分析得到。The photogenerated electron and hole current densities caused by light can be analyzed as follows.

波长为λ的光照功率为P_in，有效光照面积为A_i，那么光子通量表面密度列为式(9)，The light power with wavelength λ is P _in , and the effective light area is A _i , then the surface density of photon flux is listed as formula (9),

式中R′(x)[n_s(λ)-n_a(λ)]/[n_s(λ)+n_a(λ)]是半导体材料的反射率，n_s(λ)和n_a(λ)是波长为λ的光在半导体和空气中的折射率。已知光照功率P_in，在本发明具体实施例一光敏型SiC异构结多势垒变容二极管内吸收光的3C-SiC区域中任意点x的电子-空穴对(e-h-p)生成率，列为式(10)，where R′(x)[n _s (λ)-n _a (λ)]/[n _s (λ)+n _a (λ)] is the reflectivity of the semiconductor material, n _s (λ) and n _a ( λ) is the refractive index of light of wavelength λ in semiconductors and air. Knowing the light power P _in , the electron-hole pair (ehp) generation rate at any point x in the 3C-SiC region that absorbs light in the photosensitive SiC heterogeneous junction multi-barrier varactor diode in the specific embodiment of the present invention, is listed as formula (10),

G_L(λ)＝η_in(λ)α(λ)φ₀(λ)exp[-α(λ)x], (10)G _L (λ)=η _in (λ)α(λ)φ ₀ (λ)exp[-α(λ)x], (10)

式中η_in(λ)和α(λ)分别为内量子效率和3C-SiC对波长为λ的光的吸收系数。则波长为λ的光照引起的光生电子流密度J_oe列为式(11)，where η _in (λ) and α (λ) are the internal quantum efficiency and the absorption coefficient of 3C-SiC for light with a wavelength of λ, respectively. Then the photogenerated electron current density _Jo caused by light with wavelength λ is listed as formula (11),

J_oe(x)＝-q∫G_L(λ)dx＝qη_in(λ)φ₀(λ){exp[α(λ)x_n+]-exp[-α(λ)x_p+]}, (11)Joe (x)=- _q∫GL (λ)dx= _{qη in} (λ)φ ₀ (λ){exp[α(λ)x _n+ ]-exp[-α(λ)x _p+ ]}, ( 11)

式中x_n+和x_p+分别为N⁺/N、N/N⁺界面的位置。where x _n+ and x _p+ are the positions of the N ⁺ /N and N/N ⁺ interfaces, respectively.

一般地，光生电子电流密度J_oe与光生空穴电流密度J_oh大小相等、方向相反，即：In general, the photogenerated electron current density _Jo is equal to the photogenerated hole current density _Joh in opposite directions, namely:

J_oe＝-J_oh, (12) _Joe = _-Joh , (12)

因为本发明具体实施例一的光敏型SiC异构结多势垒变容二极管的N⁺型衬底、N⁺型接触层内电场为零，电流在这2个区域内通过扩散产生。通过求解满足适当边界条件的一维双极性传输方程，可得到在N⁺型衬底、N⁺型接触层的光生电子、空穴的电流密度，列为式(13)、(14)，Because the electric field in the N ⁺ type substrate and N ⁺ type contact layer of the photosensitive SiC heterojunction multi-barrier varactor diode according to the first embodiment of the present invention is zero, the current is generated by diffusion in these two regions. By solving the one-dimensional bipolar transport equation satisfying appropriate boundary conditions, the current densities of photogenerated electrons and holes in the N ⁺ -type substrate and N ⁺ -type contact layer can be obtained, which are listed as equations (13), (14),

式中L_e、L_h分别是电子、空穴的扩散长度。where L _e and L _h are the diffusion lengths of electrons and holes, respectively.

包括位移电流密度

在内，总的电流密度列为式(15)，including displacement current density

, the total current density is listed as Eq. (15),

本发明具体实施例一的光敏型SiC异构结多势垒变容二极管中载流子的传导应当遵守的电子电流密度(J_n)、空穴电流密度(J_p)的连续性方程分别列为式(16)和(17)，The continuity equations of the electron current density (J _n ) and the hole current density (J _p ) that the conduction of carriers in the photosensitive SiC heterogeneous junction multi-barrier varactor diode according to the first embodiment of the present invention are listed respectively. are equations (16) and (17),

联立求解方程式(1)、(5)、(6)、(16)、(17)，可以得到电场强度E(x)的分布。利用下式(18)，可以计算电容器储存的能量W，Solving equations (1), (5), (6), (16), (17) simultaneously, the distribution of the electric field intensity E(x) can be obtained. Using the following equation (18), the energy stored in the capacitor, W, can be calculated,

因此，可以计算本发明具体实施例一光敏型SiC异构结多势垒变容二极管的电容C，列为式(19)，Therefore, the capacitance C of the photosensitive SiC heterogeneous junction multi-barrier varactor diode in the specific embodiment of the present invention can be calculated, and it is listed as formula (19),

当然，也可以通过计算本发明具体实施例一光敏型SiC异构结多势垒变容二极管的等效电容阳极或者阴极的电荷量来获得电容C，Of course, the capacitance C can also be obtained by calculating the charge amount of the equivalent capacitance anode or cathode of the photosensitive SiC heterogeneous junction multi-barrier varactor diode in the specific embodiment of the present invention,

Q_n＝∑∫ρdV+∑n₂＝∑∫q(P-N+N_D-N_A)dV+∑n₂, (20)Q _n =∑∫ρdV+∑n ₂ =∑∫q(P-N+N _D -N _A )dV+∑n ₂ , (20)

本发明具体实施例一光敏型SiC异构结多势垒变容二极管的电容C，列为式(21)，The capacitance C of the photosensitive SiC heterogeneous junction multi-barrier varactor diode in the specific embodiment of the present invention is listed as formula (21),

本发明具体实施例一数值计算使用的参数中，N⁺型3C-SiC衬底、N型3C-SiC调制层的厚度分别为5.0×10^-6米、2.0×10^-7米，本征4H-SiC势垒层的厚度为3.0×10^-8米，N⁺型3C-SiC衬底、N型3C-SiC调制层的掺杂浓度分别为1.0×10²⁵米^-3、2.0×10²²米^-3，异构结半径4.0×10^-4米＝4.0×10²微米，3C-SiC、4H-SiC材料的参数来自网站http://www.ioffe.rssi.ru/SVA/NSM/Semicond/index.html。边界条件主要由电场在异构结界面的连续性决定；

方程中的电子波函数当作平面波来处理，到达异构结界面时一部分反射，另一部分则透射。数值模拟得到3C/4H-SiC异构结多势垒变容二极管的电容-电压(C-V)关系如图4所示。其中，2、4周期3C/4H-SiC异构结多势垒变容二极管的0偏压电容只有10余pF，非常小；2个周期异构结时的电容大于4个周期异构结时的电容，可以按照图2理解为，变容二极管包含的异构结的周期越少，串联的电容器越少，等效电容越大；偏压接近±3V时，各个变容二极管的电容值趋近于0，是因为各个变容二极管的耗尽区几乎完全耗尽，净余电荷接近为0，因此电容值趋近于0；有光照时的电容更大，可以按照图2理解为，光照区域的3C/4H-SiC异构结中3C-SiC吸收绿光形成的光生载流子正好落在3C-SiC势阱区，部分载流子因热耗散、复合等减少之外，其余的补充增加了势阱区域的净余电荷量，所以电容值增大，如图4所示；异构结界面自发极化引起的2DEG增加了势阱区域的净余电荷量，所以电容值增大，因为2DEG的值很小，电容值增大不明显，未在图4中示出；在0—±3V电压范围，电容变化不剧烈，无论用于倍频器、调谐器、参数放大器，输入信号的幅度可以比较大，即动态负载调制范围宽。In the parameters used in the numerical calculation in the specific embodiment of the present invention, the thicknesses of the N ⁺ type 3C-SiC substrate and the N type 3C-SiC modulation layer are respectively 5.0×10 ^-6 m and 2.0×10 ^-7 m, and the intrinsic 4H The thickness of the -SiC barrier layer is 3.0×10 ^-8 m, and the doping concentrations of the N ⁺ type 3C-SiC substrate and the N-type 3C-SiC modulation layer are 1.0×10 ²⁵ m ^-3 and 2.0×10 ²² m, respectively ^-3 , radius of heterojunction 4.0×10 ^-4 m = 4.0×10 ² μm, parameters of 3C-SiC, 4H-SiC materials from website http://www.ioffe.rssi.ru/SVA/NSM/Semicond/ index.html. The boundary conditions are mainly determined by the continuity of the electric field at the heterogeneous junction interface;

The electron wave function in the equation is treated as a plane wave, and when it reaches the interface of the heterogeneous junction, part of it is reflected and the other part is transmitted. The capacitance-voltage (CV) relationship of the 3C/4H-SiC heterogeneous junction multi-barrier varactor diode obtained by numerical simulation is shown in Figure 4. Among them, the 0-bias capacitance of the 2 and 4-cycle 3C/4H-SiC heterogeneous junction multi-barrier varactors is only more than 10 pF, which is very small; the capacitance of 2-cycle heterogeneous junctions is greater than that of 4-cycle heterogeneous junctions According to Figure 2, it can be understood that the less the period of the heterogeneous junction contained in the varactor diode, the fewer capacitors connected in series, and the larger the equivalent capacitance; when the bias voltage is close to ±3V, the capacitance value of each varactor diode tends to be It is close to 0 because the depletion area of each varactor diode is almost completely depleted, and the net residual charge is close to 0, so the capacitance value is close to 0; The photogenerated carriers formed by the absorption of green light by 3C-SiC in the 3C/4H-SiC heterojunction in the region just fall in the 3C-SiC potential well region, and some of the carriers are reduced due to thermal dissipation and recombination. The addition increases the net residual charge in the potential well region, so the capacitance value increases, as shown in Figure 4; the 2DEG caused by spontaneous polarization at the heterogeneous junction interface increases the net residual charge in the potential well region, so the capacitance value increases , because the value of 2DEG is very small, the increase in capacitance value is not obvious, which is not shown in Figure 4; in the voltage range of 0—±3V, the capacitance changes are not severe, whether it is used for frequency multipliers, tuners, and parametric amplifiers, the input The amplitude of the signal can be relatively large, that is, the dynamic load modulation range is wide.

本发明具体实施例一通过数值模拟得到3C/4H-SiC异构结多势垒变容二极管的电流-电压(I-V)关系曲线如图5所示。其中，2个周期异构结二极管的电流大于4个周期异构结二极管的电流，可以理解为，变容二极管包含的异构结的周期越少，串联的电阻数量越少，等效电阻值越小，因而电流强度越大。有光照时的电流更大，可以理解为，光照在3C-SiC阱中产生的光生载流子增加了传导的总载流子数，所以电流强度增大。高电压时，越过3C/4H-SiC异构结势垒的电荷显著增加，光生载流子效应相对减弱；因此电压较高时，有、无光照的I-V关系曲线差异不明显。在0—±3V电压范围，电容变化不剧烈，无论用于倍频器、调谐器、参数放大器，输入信号的幅度可以比较大，即动态负载调制范围宽。Embodiment 1 of the present invention obtains the current-voltage (I-V) relationship curve of the 3C/4H-SiC heterogeneous junction multi-barrier varactor diode through numerical simulation as shown in FIG. 5 . Among them, the current of the 2-cycle heterogeneous junction diode is greater than the current of the 4-cycle heterogeneous junction diode. It can be understood that the fewer the cycles of the heterogeneous junction contained in the varactor diode, the less the number of resistors connected in series, and the equivalent resistance value The smaller the current, the higher the current intensity. The current is larger when there is light, which can be understood as the photogenerated carriers generated by light in the 3C-SiC well, which increases the total number of carriers that are conducted, so the current intensity increases. At high voltage, the charge across the 3C/4H-SiC heterojunction barrier increases significantly, and the photogenerated carrier effect is relatively weakened; therefore, at high voltage, the difference between the I-V curves with and without illumination is not obvious. In the voltage range of 0-±3V, the capacitance does not change drastically. Whether it is used for frequency multipliers, tuners, or parametric amplifiers, the amplitude of the input signal can be relatively large, that is, the dynamic load modulation range is wide.

相对于文献[7]，本发明的光敏型SiC异构结多势垒变容二极管的电容调制比C_max/C_min、漏电流J₀更小，更适应高频、大功率的需求。Compared with the literature [7], the capacitance modulation ratio of the photosensitive SiC heterogeneous junction multi-barrier varactor diode of the present invention is smaller than C _max /C _min and leakage current J ₀ , which is more suitable for high frequency and high power requirements.

本发明实施例的有益效果：Beneficial effects of the embodiments of the present invention:

(1)本发明提出的光敏型SiC异构结多势垒变容二极管，由于SiC材料的优势，本发明实施例一的SiC异构结多势垒变容二极管具有电容小、耐压高、变容比率高、截止频率高、动态负载调制范围宽、近似线性调节等优点；(1) The photosensitive SiC heterogeneous junction multi-barrier varactor diode proposed in the present invention, due to the advantages of SiC materials, the SiC heterogeneous junction multi-barrier varactor diode in the first embodiment of the present invention has the advantages of small capacitance, high withstand voltage, High variable capacitance ratio, high cut-off frequency, wide dynamic load modulation range, approximate linear adjustment, etc.;

(2)本发明实施例一设计的光敏型SiC异构结多势垒变容二极管具有电容——电压关系关于0电压对称的特征，奇次谐波倍频电路中无需偶次谐波的空载电路，电路设计简化；(2) The photosensitive SiC heterogeneous junction multi-barrier varactor diode designed in the first embodiment of the present invention has the characteristic that the capacitance-voltage relationship is symmetrical about 0 voltage, and the odd harmonic frequency doubling circuit does not need the empty space of the even harmonic. Load circuit, circuit design is simplified;

(3)本发明实施例一除了利用传统的异质结势垒高度、势阱宽度等因素来调控电容——电压关系外，还能利用SiC异构结的自发极化效应、光照调节电容，增加了异质结势垒变容二极管的设计自由度；(3) In the first embodiment of the present invention, in addition to using the traditional heterojunction barrier height, potential well width and other factors to regulate the capacitance-voltage relationship, the spontaneous polarization effect and illumination of the SiC heterojunction can also be used to adjust the capacitance, Increased design freedom for heterojunction barrier varactors;

(4)本发明实施例一观测到光照改变电容——电压关系，即：在光照条件下，可以通过光照引起的电容——电压关系的变化反映光照的情况，也就是说，本发明实施例也是一种电容式光探测器，具有高的光探测灵敏度；(4) In the first embodiment of the present invention, it was observed that illumination changes the capacitance-voltage relationship, that is, under illumination conditions, the change in the capacitance-voltage relationship caused by illumination can reflect the illumination situation, that is, the embodiment of the present invention It is also a capacitive photodetector with high photodetection sensitivity;

(5)本发明实施例一不仅是单个器件，也为光电集成提供思路。(5) The first embodiment of the present invention is not only a single device, but also provides ideas for optoelectronic integration.

以上所揭露的仅为本发明较佳实施例而已，当然不能以此来限定本发明之权利范围，因此依本发明权利要求所作的等同变化，仍属本发明所涵盖的范围。The above disclosures are only preferred embodiments of the present invention, and of course, the scope of the rights of the present invention cannot be limited by this. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.