Comparative study on stability and electronic properties of two-dimensional Al_xGa_(1-x)N/GaN heterostructure with variable Al contents

摘要

A heterostructure with variable Al contents have been used in emission layer of photocathode to improve quantum efficiency, because difference in Al content of adjacent sublayers would generate a built-in electric field to help electron transport. In this article, based on use of first principles, we have studied structure, stability and electronic features of AlxGa1-xN/GaN heterostructure. The AlxGa1-xN/GaN heterostructure is obtained by finding the most stable stacking situation of bilayer GaN and introducing Al content in bottom layer. The cohesive energy, band structure and density of states are calculated. The results revel that introduction of Al content can increase cohesive energy of multilayer GaN and make system more stable. It will also magnify band gap of heterostructure. The results of DOS show that increasing of Al content in AlxGa1-xN monolayer enhance contribution of Al s-orbitals and p-orbitals, while contribution of Ga s-orbitals and p-orbitals decline. Finally, through analysis of stability and electronic properties of AlxGa1-xN/AlyGa1-yN heterostructure, we have found that influence of size of Al contents far exceeds that of position of Al atom.