长波长InGaAs扩散结PIN光电二极管正面入光结构的理论分析

Theoretical Analysis of Front Illuminated Structure for Long Wavelength InGaAs Diffusion PIN Photodiode

本文指出,对扩散pn结的正面入光结构,突变结理论有一定局限性。由于p^+区内杂质浓度的分布,在扩散区中存在十分强的自建漂移场,因而光生载流子将在自建场的作用下漂移进pn结内。由于载流子的漂移速度V_d远大于扩散速度V_f,因此可制得性能优异的PIN光电二极管,制作工艺比背面入光结构简单。已制得光电响应时间低达80ps的正面入光PIN二极管。

This paper indicates that the abrupt junction theory has somel imitations for the front illuminated structure of diffusion pn-junction. Because of the profile of doping density in p+ region, there exists a very large build-in drift field in diffusion region, by which photoproduced carriers are drifted into pa junction. As the carrier drift velocity vd is much larger than the diffusion velocity vf, superiorfront-illuminated diffusion PIN photodiodes——the photoresponse time is up to 80ps——are fabricated with a simpler technology compared with the back-illuminatedstructure.