高耐压和低暗计数SiC紫外雪崩光电二极管  

SiC UV Avalanche Photodiode with High Voltage Withstanding Capability and Low Dark Count Rate

作　　者：杨成东 夏开鹏 马文烨 高晏琦 郁智豪 苏琳琳 Yang Chengdong;Xia Kaipeng;Ma Wenye;Gao Yanqi;Yu Zhihao;Su Linlin(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：《光学学报》2023年第3期1-6,共6页Acta Optica Sinica

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

摘　　要：碳化硅(SiC)雪崩光电二极管(APD)是一种独具优势的微弱紫外光探测器,其过偏压承受能力是确保器件可靠工作的一个重要因素。本工作设计并制备了穿通型SiC吸收层电荷控制层雪崩倍增层分离(SACM)APD。基于这种结构,器件电场从雪崩倍增层向吸收层扩展,从而减小了雪崩倍增层内电场强度变化率,最终将器件过偏压承受能力提高到10 V;得益于吸收层的分压,雪崩倍增层的电场强度得到有效降低,载流子隧穿可能性减小,这能够有效降低器件暗计数,从而有利于提高器件探测灵敏度;此外,设计的SiC SACM APD倾斜台面仅刻蚀到雪崩倍增层上表面,这能够让器件填充因子提高至约60%,显著改善了深刻蚀导致的传统SACM结构有效光敏区域减小的问题。Objective As a weak ultraviolet(UV)detector with unique advantages,SiC avalanche photodiodes(APDs)are imperative in many key fields,such as environmental monitoring,corona detection,missile plume detection,deep space detection,and ultraviolet communication.A SiC APD is highly susceptible to irreversible thermal breakdown as its current is extremely sensitive to the bias voltage when it works under the condition of a critical electric field.Therefore,the overbias voltage withstanding capability of a SiC APD is a key issue affecting the working stability of the APD.In addition,the dark count rate is an important parameter that determines the detection sensitivity of the APD in weak UV detection.However,the reported SiC APDs exhibit low overbias voltage withstanding capabilities and high dark count rates.SiC APDs with high overbias voltage withstanding capabilities and low dark count rate have been designed and fabricated in this study.Methods In this study,SiC separated-absorption-charge-multiplication(SACM)APDs have been designed and fabricated.The SiC APDs are fabricated on n+type 4HSiC substrates(Fig.1).The epitaxial structure of the SiC APDs consists of a 10-µm p type contact layer,a 0.65-µm n-type multiplication layer,a 0.15-µm n type charge control layer,a 0.6-µm n-type absorption layer,and a 0.2-µm n type contact layer from bottom to top.The fabrication process starts with mesa etching down to the multiplication layer(to an etching depth of 1.05µm)by inductively coupled plasma etching.The photoresist reflow technique is employed to obtain a positive beveled mesa(with a small slope angle of about 5°)and thereby prevent mesa edge breakdown.Then,the epitaxial wafer is etched to the bottom contact layer.Subsequently,the APD surface is passivated by a thermal oxidation layer and then by a SiO_(2) layer deposited by plasmaenhanced chemical vapor deposition.Both the ntype and ptype Ohmic contact electrodes adopt Ni/Ti/Al/Au(35 nm/50 nm/100 nm/100 nm)layers deposited by ebeam evaporation.Finally,the epitaxial

关 键 词：探测器 雪崩光电二极管 碳化硅 微弱紫外光探测器 暗计数 过偏压承受能力 

分 类 号：O47[理学—半导体物理]