Anisotropically biaxial strain in non-polar (112\u20130) plane InxGa1\u2212xN/GaN layers investigated by X-ray reciprocal space mapping

Guijuan Zhao,Huijie Li,Hongyuan Wei,Zesheng Ji,Shaoyan Yang,Zhanguo Wang,Fangzheng Li,Yulin Meng,Lianshan Wang

doi:10.1038/s41598-017-04854-8

Abstract

In this study, the indium composition x as well as the anisotropically biaxial strain in non-polar a-plane InxGa1−xN on GaN is studied by X-ray diffraction (XRD) analysis. In accordance with XRD reciprocal lattice space mapping, with increasing indium composition, the maximum of the InxGa1−xN reciprocal lattice points progressively shifts from a fully compressive strained to a fully relaxed position, then to reversed tensile strained. To fully understand the strain in the ternary alloy layers, it is helpful to grow high-quality device structures using a-plane nitrides. As the layer thickness increases, the strain of InxGa1−xN layer releases through surface roughening and the 3D growth-mode.

Highlights

Nitride-based semiconductors are very promising materials for optoelectronic devices, in particular ultraviolet light emitting diodes (UV-LED)[1, 2]
The a-plane InxGa1−xN/ GaN heterostructures suffer from anisotropically biaxial in-plane strain which is very complex
The non-polar a-plane InxGa1−xN/GaN layers grown on r-plane sapphire with different indium content has been thoroughly researched by X-ray diffraction (XRD) method

Summary

Introduction

Nitride-based semiconductors are very promising materials for optoelectronic devices, in particular ultraviolet light emitting diodes (UV-LED)[1, 2]. In the past few years, our group has been attempting the epitaxial growth of the non-polar (1120) GaN, InxGa1−xN and semi-polar (1122) GaN6–10. To grow high-quality device structures using a-plane nitrides, it is essential to fully understand the strain in the ternary alloy layers. The a-plane InxGa1−xN/ GaN heterostructures suffer from anisotropically biaxial in-plane strain which is very complex. The X-ray method offers an essential tool to investigate the structural information of defective and distorted crystals. Reciprocal space mapping (RSM) by high-resolution X-ray diffraction (HRXRD) is ideally suited to research the detailed structural characterization of imperfect layer crystal structure such as nitrides[12, 14]. The non-polar a-plane InxGa1−xN/GaN layers grown on r-plane sapphire with different indium content has been thoroughly researched by XRD method. We illustrate the potential of RSM to extract information on the process of Indium incorporation x during InxGa1−xN growth

Methods

Results

Conclusion