空穴主导雪崩倍增的短波长SiC紫外单光子探测器  

Short-Wavelength SiC Ultraviolet Single Photon Detector Based on Hole-Dominated Avalanche Multiplication

作　　者：苏琳琳 杨成东 Su Linlin;Yang Chengdong(School of Electronic Information Engineering,Wuxi University,Wuxi 214105,Jiangsu,China)

机构地区：[1]无锡学院电子信息工程学院,江苏无锡214105

出　　处：《中国激光》2023年第18期227-231,共5页Chinese Journal of Lasers

基　　金：国家自然科学基金(62106111);无锡学院引进人才科研启动专项经费(2021r011,2021r012)。

摘　　要：制备并分析了SiC nip雪崩光电二极管(APDs)雪崩倍增的物理机制。与280 nm紫外光相比,在240 nm紫外光入射时,SiC nip APD表现出更高的增益和更大的单光子探测效率。在240 nm紫外光入射时,SiC nip APD表现为空穴主导碰撞离化过程,随着入射光波长增加到280 nm,电子和空穴共同主导碰撞离化过程。由于SiC中空穴的碰撞离化系数大于电子,空穴主导的碰撞离化过程将具有更大的光子雪崩概率和更高的增益。因此,得益于空穴主导雪崩倍增过程,SiC nip APD更适用于短波长紫外光探测。Objective SiC avalanche photodiodes(APDs)have the merits of visible light blindness,low weight,and high gain,exhibiting obvious advantages in weak ultraviolet detection.SiC APDs are mostly designed as pn junction structures,which can be divided into pin and nip APDs,according to the distribution of the epitaxial layers.When the SiC APD is conducting weak light detection,the device works under the avalanche state;the SiC pin and nip APDs exhibit completely opposite carrier drift directions.Holes in the pin APD drift toward the p-type layer,that is,the device surface,whereas the electrons drift toward the n-type layer,that is,the substrate;the nip APD exhibits the opposite.Cha et al.estimated the absorption coefficient of SiC at room temperature,and the results showed that SiC has a higher absorption coefficient for high-energy photons.Therefore,for the SiC pin and nip APDs,owing to the difference of the carrier drift direction,the types of carriers that cause collision ionization may be different for different wavelength detections.Considering that the collision ionization coefficient of holes in SiC is larger than that of electrons,different types of collision ionization carriers will certainly affect the detection performance of APDs.In this work,SiC nip APDs are designed and fabricated with a higher single photon detection efficiency for short wavelength ultraviolet light,benefitting from the hole dominated collision ionization process.This work is conducive for the in-depth understanding of the working mechanism of SiC APD and provides theoretical guidance for its optimization in the future.Methods The SiC nip APD is fabricated on an n-type 4H-SiC substrate(Fig.1).The epitaxial structure is a 10μm thick p-type contact layer(acceptor doping concentration NA=3×1018 cm-3),a 0.05μm thick transition layer,a 0.7μm thick n-type avalanche multiplication layer(donor doping concentration ND=1×1015 cm-3),a 0.2μm thick n-type transition layer(ND=1×1018 cm-3),and a 0.15μm thick n-type contact layer(ND=1×1019 cm-3)

关 键 词：激光器 SIC 雪崩光电二极管 深紫外光探测 光子雪崩概率 

分 类 号：O475[理学—半导体物理]