氮化物子带跃迁探测器材料结构对器件效率的影响  

Effects of material structure on device efficiency of Ⅲ-nitride intersubband photodetectors

作　　者：康健彬 李倩[1,2] 李沫[1,2] Kang Jian-Bin;Li Qian;Li Mo(Microsystem and Terahertz Research Center,China Academy of Engineering Physics,Chengdu 610200,China;Insititute of Electronic Engineering,China Academy of Engineering Physics,Mianyang 621999,China)

机构地区：[1]中国工程物理研究院微系统与太赫兹研究中心,成都610200 [2]中国工程物理研究院电子工程研究所,绵阳621999

出　　处：《物理学报》2019年第22期409-417,共9页Acta Physica Sinica

基　　金：科学挑战专题(批准号:TZ2016003);国家自然科学基金(批准号:61804141,61704163)资助的课题~~

摘　　要：氮化物子带跃迁探测器具备在近红外通讯波段高速工作和在太赫兹波段室温工作的潜力,但材料强的极化作用容易造成器件效率降低.本文分别针对工作于上述波段的典型器件,理论分析了材料结构参数对器件能带结构、载流子浓度分布、极化效应以及光生载流子隧穿的影响.近红外波段器件以光伏型器件结构为基础,研究发现增加量子势阱的周期数、增大势阱掺杂浓度、以及保持接触层材料晶格常数与超晶格有源区平均晶格常数相同,有助于增加基态能级上被载流子填充的量子势阱数,从而增强器件的吸收效率.太赫兹波段器件以双台阶器件结构为基础,研究表明器件设计时即使任意调节势阱层和势垒层厚度,也不会改变影响光生载流子传输的势垒层极化电场分布.同时,降低台阶势垒层铝组分和适当增加其厚度可以提高光生载流子隧穿通过台阶势垒层的效率.本文仿真结果对于设计优化的氮化物子带跃迁探测器材料结构、提升器件性能具有指导意义.The photodetection potential applications ofⅢ-nitride semiconductor are not only restricted in the ultraviolet range,but also extended to the infrared and even terahertz wave range through intersubband transition(ISBT)process between quantum-confined electronic states.The large conduction band offset(~1.75 eV for GaN/AlN heterostructures)and the strong electron-phonon interaction in these materials enable theⅢ-nitride ISBT photodetectors to operate with ultrahigh speed for near-infrared telecommunication applications.Furthermore,due to the large energy of longitudinal optical phonons of nitride materials(~92 meV for GaN),the corresponding ISBT photodetectors are demonstrated as a promising candidate for operating in a specific terahertz(THz)range(5-12 THz)at high temperature,which is fundamentally in accessible to Asbased devices.One of the major difficulties in realizing high performanceⅢ-nitride ISBT photodetectors is the existence of undesired polarization field inherited from conventional c-axis nitrides,which greatly makes the design complicated.In this paper,we theoretically study the influences of critical material structure parameters on the band structure,electron distribution,polarization field intensity,and tunneling effect based on nearinfrared photovoltaic photodetectors and terahertz double-step photodetectors.Ⅲ-nitride ISBT photodetectors operating in near-infrared are designed to be able to suppress the internal electric field in the active region,so that as many quantum wells as possible can be populated by electrons to enhance the absorption efficiency.It is found that with the increase of well periods and well doping concentration,a weaker average polarization field is observed,and as a result more wells will be populated with electrons.In addition,keeping the lattice constant of the contact layer material the same as the average lattice constant of the active region is beneficial to making more quantum wells effectively populated with electrons.On the other hand,the devices operating i

关 键 词：氮化物 子带跃迁 探测器 量子势阱 

分 类 号：TN3[电子电信—物理电子学]