Band structure of Ge1−xSnx alloy: a full-zone 30-band k · p model

Zhigang Song,Chuan Seng Tan,Dao Hua Zhang,Greg Sun,Weijun Fan,Qijie Wang,Donguk Nam

doi:10.1088/1367-2630/ab306f

Zhigang Song, Chuan Seng Tan + Show 5 more

Open Access

https://doi.org/10.1088/1367-2630/ab306f

Copy DOI

Abstract

A full-zone 30-band k · p model is developed as an efficient and reliable tool to compute electronic band structure in Ge1−xSnx alloy. The model was first used to reproduce the electronic band structures in Ge and α-Sn obtained with empirical tight binding and ab initio methods. Input parameters for the 30-band k · p model are carefully calibrated against prior empirical predications and experimental data. Important material properties such as effective mass for electrons and holes, Luttinger parameters, and density of states are obtained for Ge1−xSnx alloy with the composition range 0 < x < 0.3. The 30-band k · p model that requires far less computing resources is a necessary capability for optimization of sophisticated devices made from Ge1−xSnx alloy with a large parameter space to explore.

Highlights

The field of Si photonics has seen impressive growth since the early vision in 1990s [1]
This task is complicated by the fact that many material parameters remain unknown for a wide range of alloy compositions that need to be extracted from electronic band structures across the entire Brillion zone (BZ)
In this work we present the results of effective masses along different crystalline directions, Luttinger parameters, and density of states (DOS) at Γ and L valleys for relaxed Ge1−xSnx alloys spanning across the alloy composition range 0.0 < x < 0.3 at room temperature

Summary

Introduction

The field of Si photonics has seen impressive growth since the early vision in 1990s [1]. The progress in developing actual light sources has been painfully slow due to the grand technical challenges in growing high quality SiGeSn materials with sufficient Sn to turn the materials into direct bandgap. There is reason to be optimistic that the grand prize this material system has to offer, i.e. electrically pumped GeSn laser diodes, is within reach and the community will soon be facing the task of device performance optimization. This task is complicated by the fact that many material parameters remain unknown for a wide range of alloy compositions that need to be extracted from electronic band structures across the entire Brillion zone (BZ)

Objectives

Results

Conclusion