InP基InGaAsBi材料及其短波红外探测器研究

Short-wave infrared photodetectors with cut-off wavelength beyond 1.7 μm have many important applications. This project proposes to demonstrate short-wave infrared photodetectors with cut-off wavelength longer than 2.5 μm by using InP-based novel InGaAsBi materials. The large band-gap bowing effect of dilute bismide is applied to overcome the lattice mismatch issue of InP-based wavelength-extended InGaAs photodetectors with high indium composition. Recently, we have grown some InGaAsBi materials with various compositions, and demonstrated InGaAsBi prototype photodetector with cut-off wavelength at 2.1 μm. The surfactant effects of bismuth on improving the material quality have also been investigated. These former studies definitely prove the feasibility of this project and clarify the key scientific issues. This project will aim for uncovering physical properties of novel InGaAsBi materials and demonstrating short-wave infrared photodetectors. The basic theory of InGaAsBi materials will be revealed and the bismuth incorporation performance under different growth conditions of molecular beam epitaxy will be assessed. The effects of bismuth incorporation on the material properties of InGaAsBi will also be studied, while the key parameters, e.g. the band structure, absorption coefficient and minority carrier lifetime, will be obtained. After well knowing the properties of InGaAsBi, we intend to study the structure design, material growth and device physics of the photodetectors, endeavor to decrease dark current and enhance quantum efficiency, and develop high performance InP-based InGaAsBi short-wave infrared photodetectors.

截止波长大于1.7微米的短波红外探测器具有许多重要的应用。本项目提出基于InP基InGaAsBi新材料研究截止波长大于2.5微米短波红外探测器的新思路，利用稀铋材料大的带隙收缩特性，克服InP基高铟组分InGaAs探测器的晶格失配问题。在前期预研工作中已生长了不同组分的InGaAsBi材料，并演示了截止波长2.1微米的原型探测器，还发现了铋作为表面剂改善材料质量的明显效果，证实了此项目的可行性。本项目将以认知InGaAsBi新材料的物理特性及研制短波红外探测器为目标，开展InGaAsBi材料基础理论和实验研究，探究不同分子束外延生长条件下铋元素的行为，分析铋的引入对InGaAsBi材料特性的影响，获取材料能带结构、吸收系数、少子寿命等关键参数。开展探测器结构设计、材料生长和器件物理研究，围绕降低器件暗电流和提高量子效率，研制高性能InP基InGaAsBi短波红外探测器。

截止波长大于1.7微米的短波红外探测器在超光谱成像、矿产资源探测等信息探测和获取方面具有许多重要的作用。本项目提出利用稀铋材料大的带隙收缩特性，基于InP基InGaAsBi新材料研究截止波长大于2.5微米短波红外探测器的新思路。.项目主要研究内容包括研究铋凝入对InGaAsBi材料物性参数的调控，优化生长InGaAsBi材料的生长条件，比较不同生长条件下铋元素的凝入行为和对材料物性的影响。设计并生长InP基InGaAsBi探测器结构材料，优化生长工艺，开展材料测试分析。优化InGaAsBi探测器器件工艺，研究器件暗电流、光谱响应及其温度特性，提升器件性能。.本项目实现了分子束外延InGaAsBi材料生长优化。发现在不同Bi组分情况下，InGaAsBi材料在不同温度下的电子浓度和迁移率呈现出特定的规律，对其机理进行了详细分析，发现其原子空位、团簇、晶格或电离杂质散射等因素有关。获得InGaAsBi材料的能带收缩系数56.4meV/Bi%，材料发光强度随着Bi组分的增加逐渐降低，禁带宽度随温度变化的温度系数为0.06meV/K，远小于InGaAs对比样品的0.14meV/K，说明InGaAsBi材料对温度变化更不敏感。.采用变温低频噪声光谱对InGaAsBi探测器进行了测试，材料中的三个深能级杂质的能级Ec-0.33eV、Ev+0.14eV和Ec-0.51eV，与光致发光所得到的深能级位置接近。.进一步降低了材料禁带宽度至0.47eV，材料AFM表面粗糙度为5.4nm。设计提出采用氮化铝/氮化硅双层钝化膜实现对台面侧壁的有效覆盖，从而提升绝缘钝化性能。器件室温下截止波长为2.63μm，在1550nm处的响应度是0.61A/W，波长温度系数仅为0.96nm/K。器件300K和77K情况下-10mV偏压暗电流分别为1.12E-5A和6.52E-8A。.本项目的研究对了解InGaAsBi 的基础材料和器件物理具有指导意义，将InGaAsBi稀铋新材料应用于探测器研制，推动对稀铋材料的研究从材料基础研究发展到器件应用研究，为具有国家重大战略需求应用的短波红外波段探测器研制提供了新的思路。