Influence Of In GaN Insertion Layer On Electron Scattering At AlGaN/GaN Interface

Compared with other GaN-based single heterojunction materials,the traditional single heterojunction material Al_xGa_1-xN/GaN has relatively strong spontaneous polarization and piezoelectric polarization,resulting in high density and high mobility at the heterojunction interface for the two-dimensional electron gas.Therefore,the single heterojunction material Al_xGa_1-xN/GaN can be widely used in the field of high-frequency and high-power semiconductor devices.In order to further improve the device performance of Al_xGa_1-xN/GaN HEMT,this paper studies the changes in electron transport properties caused by In GaN as an Al GaN/GaN insertion layer.At the sametime,we considered the influence of the spontaneous polarization and piezoelectric polarization of Al GaN and In GaN barrier layers to Al_xGa_1-xN/In_yGa_1-yN/GaN double heterojunction high electron mobility transistor for the polarization charge surface density and two-dimensional electron.In addition,the relationship between the thickness of the In GaN barrier layer and the scattering of interface roughness,random dipole scattering,alloy disorder scattering and polar optical phonon scattering under different In composition are analyzed.This article starts with the method used to prepare double heterojunction Al_xGa_1-xN/In_yGa_1-yN/GaN and introduces the properties and structure of double heterojunction Al_xGa_1-xN/In_yGa_1-yN/GaN,as well as interface polarization charge density and piezoelectric polarization Calculation method.At the same time,a schematic diagram of the three-dimensional conduction band of the Al_xGa_1-xN/In_yGa_1-yN/GaN structure is drawn,which makes the entire electron transport process more intuitive;then the general calculation process for different types of electron scattering is given,including interface roughness scattering,Random dipole scattering,alloy disorder scattering and polar optical phonon scattering;Finally,the calculated results of carrier mobility are downloaded by different scattering types to study the common influence of In GaN insertion layer thickness and In composition content on carrier scattering mobility.The experimental results show that the interface roughness scattering and random dipole scattering have an important influence on the electron transmission performance of the double heterojunction Al_xGa_1-xN/In_yGa_1-yN/GaN.Polar optical phonon scattering has the second most effect,and the alloy scattering has the weakest influence on it;calculation results show that the strength of 2DEG concentration,alloy disorder scattering,interface roughness scattering,random dipole scattering and polar optical phonon scattering are determined by the thickness of the In GaN barrier layer and the In composition content together.The two-dimensional electron gas mobility has shown to be drastically enhanced in the Al_xGa_1-xN/In_yGa_1-yN/GaN double-heterostructure,compared with that in the conventional Al GaN/GaN single-heterostructure.Both carrier density and quantum confinement are very sensitive to the strain in the In GaN channel layer.The Al_xGa_1-xN/In_yGa_1-yN/GaN double-heterostructures are promising for field effect transistor applications because of their superior electron transport properties.