Gan-bto Heterostructure First - Principles Study On Electronic Properties

Heterojunction has been widely used in communications, microelectronics and optoelectronics and other fields for its excellent electronic transport properties and optical properties.Nowadays,Ferroelectric materials and wide bandgap semiconductors are very popular materials,people expect excellent electronic properties of the heterojunction which is composed by ferroelectric material and wide bandgap semiconductor.Based on density functional theory,this paper has researched the heterojunction GaN-BTO composed by ferroelectric material BaTiO₃ and wide bandgap semiconductor GaN by first-principle. The research is as follows:First,this paper discusses the bulk structure of the GaN and BTO,emphasis on the band-gap structure,band gap,density of state,bond properties and so on.Then,the surface of the two kinds of materials are discussed.This paper analyzes (001) surface properties,discusses the four kinds of terminated surface properties in detail,the research shows that:in the surface structure,the atoms near outer layer relax more distance,the metal atoms relax more distance then non-metallic atoms in the same layer.Ga-terminated surface is more stable then N-terminated surface,and BaO-terminated surface is more stable then TiO2-terminated surface.Next,this paper discusses the electronic properties of Nb-doped BTO and Al-doped GaN in detail.According to the research:Doping will cause the system more unstable.For the Nb-doped BTO,when the doping concentration is less then 25%,the band gap of the system will decrease as the doping concentration increasing,however,when the doping concentration is over 25%,the band gap of the system will increase as the doping concentration increasing.While Al is doped in GaN,the band gap of the system elevates,and p-orbital of valence band moves to the higher energy.At last,this paper discusses the GaN-BTO heterojunction in detail,and compares the ideal heterojunction to the doped heterojunction.During analyzing the heterojunction, we put emphasis on the electronic structural properties and band offset.