Effect of Substrate Surface on Deposition of AlGaN: A Molecular Dynamics Simulation

Libin Zhang,Sheng Liu,Zili Zhang,Guo Zhu,Zhiyin Gan,Han Yan

doi:10.3390/cryst8070279

Abstract

The growth of AlGaN has been extensively studied, but corresponding research related to the effect of AlN substrate surface has rarely been reported in literature. In this article, the effects of AlN substrate surface on deposition of AlGaN films were investigated by molecular dynamics (MD) simulations. (0001) Al-terminated and (0001¯) N-terminated AlN were considered as substrates. The quality of surface morphology and atomic scale structure of deposited AlGaN film are discussed in detail. The results show that the surface morphology and crystal quality of AlGaN film grown on (0001) Al-terminated AlN surface are better than for that grown on (0001¯) N-terminated AlN surface under various growing temperatures and Al/Ga injection ratios between Al and Ga. This can be attributed to the higher mobility of Al and Ga adatoms on the (0001) Al-terminated AlN surface. These findings can provide guidance for the preparation of high-quality AlGaN thin films on AlN substrate.

Highlights

III-Nitrides have attracted much attention over the past decades due to their excellent optoelectronic and physical properties [1,2,3]
6.2 eV), AlGaN alloys are widely used in the area of optical devices such as laser diodes (LDs) [4], light emitting diodes (LEDs) [5] and photodetectors [6]
A smooth surface is a critical indicator of high-quality AlGaN film

Summary

Introduction

III-Nitrides have attracted much attention over the past decades due to their excellent optoelectronic and physical properties [1,2,3]. In deep ultraviolet LED (DUV-LEDs), AlGaN/AlN superlattices (SLs) are used for filtering dislocations and relieving stresses [7] It is applied in n and p electrodes as the container of negative and positive carriers, respectively [8,9]. Little attention has been paid to exploring the effect of the AlN surface on the growth of AlGaN film, while the GaN surface has been systematically studied [16,17]. Characters such as surface morphology, atomic structure, defects and migration process during the growth process can be visualized directly by MD simulations.

Interatomic Potential

Simulation Details

Analysis Methods

Surface Morphology

Atomic Structure

Atomic Migration Mechanisms

Conclusions