高铝组分AlGaN半导体量子结构中的光生载流子动力学性质研究

项目名称： 高铝组分AlGaN半导体量子结构中的光生载流子动力学性质研究

项目编号： No.61475184

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 无线电电子学、电信技术

项目作者： 刘争晖

作者单位： 中国科学院苏州纳米技术与纳米仿生研究所

项目金额： 80万元

中文摘要： 高铝组分AlGaN半导体材料是制备波长280nm以下日盲紫外探测和发光器件的理想材料。高密度缺陷和铝组分不均匀性是这类材料的重要特征，其导致能带结构的不均匀性，影响载流子的激发、输运和复合，是制约器件效率的关键因素。但另一方面，缺陷和不均匀的组分本身作为量子结构，所构造的局域电场也可以改善探测增益和发光效率。因此如果能深入认识其中物理机制，揭示这些纳米尺度的结构和载流子动力学性质的对应关系，无疑可以有针对性的进行调控，突破效率瓶颈。本项目拟应用自主研发的基于光辅助扫描开尔文探针显微镜的深紫外光电压谱方法，以亚纳米的原子级空间分辨率研究单个缺陷的电荷状态和光电响应特性，定量测量强极化场下缺陷和组分不均匀性对载流子扩散长度、复合速率等动力学性质的影响。与第一性原理计算相结合，系统地探究不同掺杂和组分的材料中局域场和电子空穴对的相互作用微观过程和物理机制，为设计新型高效的深紫外光电器件奠定基础。

中文关键词： 氮化镓铝；晶体缺陷；深紫外；光电压谱；载流子动力学

英文摘要： AlGaN semiconductor with high Al content is ideal material for fabrication of solar-blind ultra-violet detectors and light-emitting diodes. The material is featured by its high density of defects and compositional inhomogeneity of Al content, which introduce inhomogeneity of inner electric field and band structures. Such inhomogeneity with the effect on the excitation, transmission and recombination of carriers may degrade the efficiency of devices. On the other hand, the inhomogeneity may also act as quantum structures with local electric field, which can improve the gain of detectors and the light emitting efficiency. So the thoroughly exploring of the physical mechanisms will help to design novel structures in devices with proper modulation of these features. However, the normally applied characterization methods without high spatial resolution are hard to reveal the relationship between the carrier dynamics and the inhomogeneity at nanometer scale. In this project, we applied the deep ultra-violet photovoltage spectrum measured by a photo-assisted Kelvin force microscope to study the opto-electric properties of single defects. The method has a spatial resolution of atomic level at sub-nanometer. We can also quantitatively measure the influence of defects and compositional inhomogeneity on the carrier dynamics including diffusion lengths and recombination velocities. By alternating the impurities and the composition of the material, the micro mechanism of opto-electric properties can be systematically studied by first-principle calculations, which are the foundation of designing novel deep ultra-violet devices with high efficiency.

英文关键词： AlGaN;crystal defects;deep ultra-violet;photovoltage spectrum;carrier dynamics