Strain mapping in interband cascade lasers

Xiaoling Ye,Tian Yu,Lijun Wang,Ruixuan Sun,Junqi Liu,Ning Zhuo,Jinchuan Zhang,Chao Ning,Yuan Li,Shenqiang Zhai,Fengqi Liu,Shu-Man Liu

doi:10.1063/5.0079193

Abstract

A typical interband cascade laser wafer contains more than 2000 multilayers composed of InAs, AlSb, GaSb, and GaInSb. The lattice constants of the three materials except GaSb have a certain degree of mismatch with the GaSb substrate. Therefore, to grow a high-quality epitaxial layer, it is necessary to optimize the growth conditions to achieve strain balance in the entire epitaxial layer. In this work, the strained superlattice structure was characterized via scanning transmission electron microscopy and high-resolution x-ray diffraction. The strain distribution was mapped using geometric phase analysis of high-angle annular dark-field images. We demonstrate that strain compensation has been achieved in both the InAs/AlSb superlattice clad layers and the InAs/InGaSb/InAs W quantum well active region.

Highlights

Antimonide-based type-II superlattice optoelectronic devices have gained much attention in recent years, owing to their high performance in the mid-infrared regime
Studies of strain distribution are important for optimizing growth conditions and band structures, which directly affect the performance of InAs/AlSb quantum cascade lasers8,9 and InAs/GaInSb infrared detectors
When a heteroepitaxial InAs, AlSb, or GaInSb layer is coherently grown on a GaSb substrate under inplane strain, a tetragonal distortion arises and causes a change in the out-of-plane lattice constant, which is usually observed via high-resolution x-ray diffraction (HRXRD)

Summary

INTRODUCTION

Antimonide-based type-II superlattice optoelectronic devices have gained much attention in recent years, owing to their high performance in the mid-infrared regime. Such devices include InAs/GaSb superlattice detectors, InAs/AlSb quantum cascade lasers (QCLs), and interband cascade lasers (ICLs).. Studies of strain distribution are important for optimizing growth conditions and band structures, which directly affect the performance of InAs/AlSb quantum cascade lasers and InAs/GaInSb infrared detectors.. When a heteroepitaxial InAs, AlSb, or GaInSb layer is coherently grown on a GaSb substrate under inplane strain, a tetragonal distortion arises and causes a change in the out-of-plane lattice constant, which is usually observed via high-resolution x-ray diffraction (HRXRD). We obtained the strain distribution via geometric phase analysis (GPA) of highangle annular dark-field (HAADF) images.

EXPERIMENTAL

RESULTS AND DISCUSSION

CONCLUSION