一种近红外宽光谱CMOS单光子雪崩二极管探测器

Research of a CMOS single photon avalanche diode detector with wide near infrared spectrum

本文提出了一种新型近红外宽光谱的CMOS单光子雪崩二极管探测器(SPAD)结构,采用深N阱与P-外延层作为主雪崩区,增强了近红外短波光子探测效率;同时在深N阱内形成两个对称的环状次雪崩区,提高了光谱的响应范围。在0.18μm CMOS工艺下对该新型SPAD结构与传统P+/Nwell结构进行了仿真比较,TCAD仿真结果表明在850nm的近红外短波波段,新型SPAD器件的光子探测效率(PDE)达到19.9%,约为P+/Nwell结构的5倍,且在300nm-1000nm宽光谱范围内器件都能得到较高的响应。此外,由于雪崩区场强低,该新型SPAD器件受带-带隧穿效应(BTBT)影响小,暗计数率(DCR)随过偏压变化小,并且在温度低于20℃时DCR都远小于P+/Nwell结构。

In this paper,a novel near-infrared wide-spectrum CMOS single-photon avalanche diode detector ( SPAD) structure is proposed.The primary avalanche region is formed between deep Nwell and Pepitaxial layer,which improves the detection efficiency of near-infrared shortwave photons. Meanwhile, there exists two secondary avalanche zones arranged in a symmetrical ring in the deep Nwell region,improving the spectral response range. The proposed novel device structure and the traditional P + /Nwell structure were compared by TCAD simulation in 0.18μm CMOS process. The simulation results show the new SPAD device arrives high photon detection efficiency of 19.9% at the 850nm near -infrared short wavelength,which is about 5 times that of the P + /Nwell structure,and can respond to single photon within a wide spectral detection range of 300nm-1000nm. In addition,due to low field strength in the avalanche region,the new SPAD structure is slightly affected by the band -to -band tunneling ( BTBT) effect,thus the dark count rate ( DCR) varies very little with the excess bias voltage and the DCR is lower than that of the P+ /Nwell structure at temperatures below 20℃.