使用二维器件模拟软件Medici,对SiC_1-xGe_x/SiC异质结的光电特性进行了模拟.设计了N型重掺杂SiC层的厚度为1μm,P型轻掺杂SiC_1-xGe_x层厚为0.4μm,二者之间形成突变异质结.在反向偏压3 V、光强度为0.23 W/cm2的条件下,p-n+SiC_0.8 Ge_o.2/SiC和p-n+SiC_0.7 Ge_0.3/SiC敏感波长λ分别可以达到0.64μm和0.7μm,光电流分别为7.765×10-7A/μm和7.438×10-1A/μm;为了进一步提高SiC_1-xGe_x/SiC异质结的光电流,我们把p-n+两层结构改进为p-i-n三层结构.在同样的偏压、光照条件下,p-i-n SiC_0.8Ge_0.2/SiC和p-i-n SiC_0.7Ge_0.3/SiC的光电流分别达到1.6734×10-6A/μm和1.844×10-6A/μm.

Abstract　Photoelectric characteristics of SiC_1-xGe_x/SiC heterojunction diode were simulated using MEDICI tools, and the simulation results are presented and discussed in this letter. The abrupt heterojunction diode is composed of a 1 μm thick heavily doped n-type SiC layer and a 0.4 μm thick lightly doped p-type SiC_1-xGe_x layer with varied composition ratios. It has been shown that photocurrent of the p- n+ SiC_1-xGe_x/SiC diode is not decreased apparently by change the composition ratio from 0.2 to 0.3 for the applied reverse-bias voltage of 3 V and the incident light intensity of 0. 23 W/cm2.Corresponding photocurrents of the diodes are 7. 765 × 10 -7 A/μm and 7. 438 × 10-7 A/ μm, and the longest wavelength limits are 0.64 μm and 0.70 μm, respectively. It has also been shown by the simulation results that p-i-n structure composed by adding a p + -SiC_1-xGe_x thin layer on top of the lightly doped p-type SiC_1-xGe_x layer is much better for obtaining a higher photocurrent. Under the same conditions, photocurrents of 1. 6734 10-6 A/μm and 1. 844 × 10-6 A/μm can be obtained in the p-i-n SiC_1-xGe_x/SiC diodes with x = 0.2 and 0.3, respectively.