Aluminium incorporation in polar, semi- and non-polar AlGaN layers: a comparative study of x-ray diffraction and optical properties

Duc V Dinh,Yoshio Honda,Nan Hu,Hiroshi Amano,Markus Pristovsek

doi:10.1038/s41598-019-52067-y

Abstract

Growth of AlxGa1−xN layers (0 ≤ x ≤ 1) simultaneously on polar (0001), semipolar (10bar{{rm{1}}}3) and (11bar{{rm{2}}}2), as well as nonpolar (10bar{{rm{1}}}0) and (11bar{{rm{2}}}0) AlN templates, which were grown on planar sapphire substrates, has been investigated by metal-organic vapour phase epitaxy. By taking into account anisotropic in-plane strain of semi- and non-polar layers, their aluminium incorporation has been determined by x-ray diffraction analysis. Optical emission energy of the layers was obtained from room-temperature photoluminescence spectra, and their effective bandgap energy was estimated from room-temperature pseudo-dielectric functions. Both x-ray diffraction and optical data consistently show that aluminium incorporation is comparable on the polar, semi- and non-polar planes.

Highlights

Growth of AlxGa1−xN layers (0 ≤ x ≤ 1) simultaneously on polar (0001), semipolar (1013) and (1122), as well as nonpolar (1010) and (1120) AlN templates, which were grown on planar sapphire substrates, has been investigated by metal-organic vapour phase epitaxy
In contrast to widely compositional studies for up to twenty various InGaN surface orientations grown on GaN substrates using metal-organic vapour phase epitaxy (MOVPE)[17,18,19,20,21,22] and ammonia molecular beam epitaxy (MBE)[23], very limited study has been performed for semi- and non-polar AlGaN grown on AlN substrates, e.g., m-plane[24], semipolar (1012)[25] and (2021)[26]
Compositional study of these layers has been investigated by x-ray diffraction (XRD), room-temperature photoluminescence (RT-PL) and pseudo-dielectric functions (DFs) measurements

Summary

Introduction

Growth of AlxGa1−xN layers (0 ≤ x ≤ 1) simultaneously on polar (0001), semipolar (1013) and (1122), as well as nonpolar (1010) and (1120) AlN templates, which were grown on planar sapphire substrates, has been investigated by metal-organic vapour phase epitaxy. In contrast to widely compositional studies for up to twenty various InGaN surface orientations grown on GaN substrates using metal-organic vapour phase epitaxy (MOVPE)[17,18,19,20,21,22] and ammonia molecular beam epitaxy (MBE)[23], very limited study has been performed for semi- and non-polar AlGaN grown on AlN substrates, e.g., m-plane[24], semipolar (1012)[25] and (2021)[26]. To extend compositional study of AlGaN with different surface orientations, in this paper, we report on MOVPE-growth of AlxGa1−xN layers simultaneously on polar (0001), semipolar (1013) and (1122), as well as nonpolar (1010) and (1120) AlN/sapphire templates over the entire range of composition Compositional study of these layers has been investigated by x-ray diffraction (XRD), room-temperature photoluminescence (RT-PL) and pseudo-dielectric functions (DFs) measurements

Methods

Results

Discussion

Conclusion