InGaN插入层对AlGaN/GaN界面电子散射的影响

Effect of inserted InGaN layer on the two-dimensional electron gas in Al_(x)Ga_(1-x)N/In_(y)Ga_(1-y)N/GaN

本文研究InGaN作为AlGaN/GaN插入层引起的电子输运性质的变化,考虑了AlGaN和InGaN势垒层的自发极化与压电极化对Al_(x)Ga_(1-x)N/In_(y)Ga_(1-y)N/GaN双异质结高电子迁移率晶体管中极化电荷面密度、二维电子气(2DEG)浓度的影响,理论分析了不同In摩尔组分下,InGaN厚度与界面粗糙度散射、随机偶极散射和极性光学声子散射之间的关系.计算结果表明:界面粗糙度散射和随机偶极散射对双异质结Al_(x)Ga_(1-x)N/In_(y)Ga_(1-y)N/GaN的电子输运性质有重要影响,极性光学声子散射对其影响最弱;2DEG浓度、界面粗糙度散射、随机偶极散射和极性光学声子散射的强弱由InGaN势垒层厚度和In摩尔组分共同决定.

This paper studies the changes in electronic transport properties caused by InGaN as an AlGaN/GaN insertion layer,and considers the effects of the spontaneous polarization and piezoelectric polarization of AlGaN and InGaN barrier layers on the surface density of polarized charge,and the concentration of two-dimensional electron gas(2DEG)in Al_(x)Ga_(1-x)N/In_(y)Ga_(1-y)N/GaN double heterojunction high-electron-mobility transistor.The InGaN thickness and interface roughness scattering,random dipole scattering and polar optical phonons under different In molar compositions are analyzed.The calculation results show that the interface roughness scattering and random dipole scattering have an important influence on the electron transport properties of the double heterojunction Al_(x)Ga_(1-x)N/In_(y)Ga_(1-y)N/GaN,and the polar optical phonon scattering has the weakest influence;2DEG concentration,the strength of interface roughness scattering,random dipole scattering and polar optical phonon scattering are determined by the thickness of the InGaN barrier layer and the molar composition of In.This paper takes 2DEG in the Al_(x)Ga_(1-x)N/In_(y)Ga_(1-y)N/GaN double heterojunction as the research object,considering the barrier layer of finite thickness,taking into account the spontaneous polarization effect and piezoelectric polarization effect of each layer,and giving Al_(x)Ga_(1-x)N/GaN 2DEG characteristics in the In_(y)Ga_(1-y)N/GaN double heterostructure,discussing the scattering of 2DEG concentration and interface roughness by changing the In molar composition and the thickness of the InGaN barrier layer under the same Al molar composition and the thickness of the AlGaN barrier layer,Random dipole scattering and polar optical phonon scattering.The results of the present study are of great significance in controlling the 2DEG concentration in the Al_(x)Ga_(1-x)N/In_(y)Ga_(1-y)N/GaN double heterojunction structure and improving the electron mobility.This paper presents the analytical expression of 2DEG concentration ns in Al_(x)Ga_(1-x)N/In_(y)Ga_(1-y)N/GaN double heterostructure.The effects of the thickness of the InGaN insertion layer and the molar composition of indium on the 2DEG concentration,interface roughness scattering,random dipole scattering and total mobility are studied.According to the theoretical calculation results,on condition that the physical properties of the AlGaN barrier layer remain unchanged,choosing the appropriate InGaN barrier layer thickness and In molar composition concentration can better control the 2DEG concentration and carrier mobility.These results are beneficial to widely using the double heterojunction Al_(x)Ga_(1-x)N/In_(y)Ga_(1-y)N/GaN in actual nitride based semiconductor devices.