Effect of Vacancy Defects on the Electronic Structure and Optical Properties of GaN

Lili Cai,Cuiju Feng

doi:10.1155/2017/6987430

Abstract

The effect of gallium vacancy (VGa) and nitrogen vacancy (VN) defects on the electronic structure and optical properties of GaN using the generalized gradient approximation method within the density functional theory were investigated. The results show that the band gap increases in GaN with vacancy defects. Crystal parameters decrease in GaN with nitrogen vacancy (GaN:VN) and increase in GaN with gallium vacancy (GaN:VGa). The Ga vacancy introduces defect levels at the top of the valence band, and the defect levels are contributed by N2p electron states. In addition, the energy band shifts to lower energy in GaN:VNand moves to higher energy in GaN:VGa. The level splitting is observed in the N2p states of GaN:VNand Ga3d states of GaN:VGa. New peaks appear in lower energy region of imaginary dielectric function in GaN:VNand GaN:VGa. The main peak moves to higher energy slightly and the intensity decreases.

Highlights

gallium vacancy (GaN) is so called third generation semiconductor materials with wide band gap
The electronic structure and optical properties of pure GaN and GaN:VN, GaN:VGa have been investigated by means of plane wave pseudopotential method (PWP) with generalized gradient approximation (GGA)
The valence band moves to higher energy regions in GaN:VGa

Summary

Introduction

GaN is so called third generation semiconductor materials with wide band gap. With the rapid developments of semiconductor technology, it has become the research focus in semiconductor materials in past decades. The GaNbased materials have the advantages of wide band gap, fast electron drift velocity, high temperature resistance, high pressure tolerance, and antiradiation [1]. They have attracted much attention in the preparation of short wavelength luminescence device and high power microwave device. Shen and Kang studied the intrinsic defects of six-party GaN and the electronic structure of C and O using local density functional theory [8]. These methods are based on first principles to calculate the formation energy of GaN and the electronic structure of C and O. We studied the effect of VGa and VN on the electronic structure and optical properties of GaN using first principles

Model and Calculation

Results and Discussions

Conclusions