双能谷效应对N型掺杂Si基Ge材料载流子晶格散射的影响  

Lattice scattering in n-type Ge-on-Si based on the unique dual-valley transitions

作　　者：黄诗浩 谢文明 汪涵聪 林光杨 王佳琪 黄巍 李成 

机构地区：[1]福建工程学院,信息科学与工程学院,福州350118 [2]厦门大学,物理科学与技术学院,厦门361005

出　　处：《物理学报》2018年第4期30-37,共8页Acta Physica Sinica

基　　金：国家自然科学基金青年基金(批准号：61604041)、福建省自然科学基金青年基金(基金号：2016J05147)、福建省教育厅2017年高校杰出青年科研人才培育计划项目和福建工程学院校科研启动基金(批准号：GY-Z14073)资助的课题.

摘　　要：性能优越的Si基高效发光材料与器件的制备一直是Si基光电集成电路中最具挑战性的课题之一.Si基Ge材料不仅与成熟的硅工艺相兼容,而且具有准直接带特性,被认为是实现Si基激光器最有希望的材料.对Si基Ge材料N型掺杂的研究有利于提示出其直接带发光增强机理.本文研究了N型掺杂Si基Ge材料导带电子的晶格散射过程.N型掺杂Si基Ge材料具有独特的双能谷(Γ能谷与L能谷)结构,它将通过以下两方面的竞争关系提高直接带导带底电子的占有率:一方面,处于Γ能谷的导带电子通过谷间光学声子的散射方式散射到L能谷;另一方面,处于L能谷的导带电子通过谷内光学声子散射以及二次谷间光学声子散射或者直接通过谷间光学声子散射的方式跃迁到Γ能谷.当掺杂浓度界于10^(17)cm^(-3)到10^(19)cm^(-3)时,适当提高N型掺杂浓度有利于提高直接带Γ能谷导带底电子占有率,进而提高Si基Ge材料直接带发光效率.Silicon-based light emitting materials and devices with high efficiency are inarguably the most challenging elements in silicon （Si） photonics. Band-gap engineering approaches, including tensile strain and n-type doping, utilized for tuning germanium （Ge） to an optical gain medium have the potential for realizing monolithic optoelectronic integrated circuit. While previous experimental research has greatly contributed to optical gain and lasing of Ge direct-gap, many efforts were made to reduce lasing threshold, including the understanding of high efficiency luminescence mechanism with tensile strain and n-type doping in Ge. This paper focuses on the theoretical analysis of lattice scattering in n-type Ge-on-Si material based on its unique dual-valley transition for further improving the efficiency luminescence of Ge direct-gap laser. Lattice scattering of carriers, including inter-valley and intra-valley scattering, influence the electron distribution between the direct Γ valley and indirect L valleys in the conduction of n-type Ge-on-Si material. This behavior can be described by theoretical model of quantum mechanics such as perturbation theory. In this paper, the lattice scatterings of intra-valley scattering in Γ valley and L valleys, and of inter-valley scattering between the direct Γ valley and L valleys in the n-type Ge-on-Si materials are exhibited based on its unique dual-valley transition by perturbation theory. The calculated average scattering times for phonon scattering in the cases of Γ valley and L valleys, and for inter-valley optical phonon scattering between Γ valley and L valleys are in agreement with experimental results, which are of significance for understanding the lattice scattering mechanism in the n-type Ge-on-Si material. The numerical calculations show that the disadvantaged inter-valley scattering of electrons from the direct Γ valley to indirect L valleys reduces the electrons dwelling in the direct Γ valley slightly with n-type doping concentration, while the strong

关 键 词：双能谷效应 晶格散射 Si基Ge材料 声子 

分 类 号：O469[理学—凝聚态物理]