SiC_(1-x)Ge_x/SiC异质结光电二极管特性的研究(英文)

Photoelectric Characteristics of SiC_(1-x) Ge_x/SiC Heterojunction Diode 

使用二维器件模拟软件Medici,对SiC_(1-x) Ge_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-x) Ge_x/SiC层厚为 0. 4μm,二者之间形成突变异质结.在反向偏压 3V、光强度为 0. 23W /cm2的条件下,p-n+SiC0. 8Ge0. 2 /SiC和p-n+SiC0. 7Ge0. 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. 765×10-7 A/μm和 7. 438×10-7 A/μm;为了进一步提高SiC1-xGex/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 nSiC0. 8Ge0. 2 /SiC和p i nSiC0. 7Ge0. 3 /SiC的光电流分别达到 1. 6734×10-6 A/μm和 1. 844×10-6 A/μm.

Photoelectric characteristics of SiC1-xGex/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 μ thick heavily doped n-type SiC layer and a 0.4 μ thick lightly doped p-type SiC1-xGex layer with varied composition ratios. It has been shown that photocurrent of the p-n+ SiC1-xGex/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+-SiC1-xGex thin layer on top of the lightly doped p-type SiC1-xGex 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 SiC1-xGex/SiC diodes with x = 0.2 and 0.3, respectively.