长波长InGaAs扩散结PIN光电二极管正面入光结构的理论分析

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。

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

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, superior front-illuminated diffusion PIN photodiodes——the photoresponse time is up to 80ps ——are fabricated with a simpler technology compared with the back-illuminated structure.