Ferroelectric / Semiconductor Heterojunction Characteristics Of The Two-dimensional Electron Gas

Because of the large switchable polarization, thermoelectricity, piezoelectricity and dielectric of ferroelectrics, it can lead new physical performances if combining ferroelectrics with semiconductor material. In this work , in order to calculate the 2DEGs and band chart in the ferroelectrics/semiconductor heterostructure , we have used charge control model and 1D Poisson Schr?dinger software; also we made use of the scattering mechanism to simulate the mobility of 2DEGs in the structure of AlGaN/GaN and BTO/GaN.Firstly, we described the methods, mechanism and applications in detail , and described the solution process and boundary conditions of 1D Poisson Schr?dinger function. We modified the source file of 1D Poisson Schr?dinger to simulate our need structure of ferroelectrics/semiconductor.1. As to ferroelectrics(BST)/GaN structure, We analysis ferroelectrics polarization, dielectric constant and gate voltage affect the 2DEG density and band in detail. We find BST/GaN strcture is more easy to form enhanced device than AlGaN/GaN structure, large polarization can induce high density 2DEG..2. As to ferroelectrics/AlGaN/GaN sturcture, we stadied that the thickness and polarization of ferroelectrics affect the 2DEG and find that positive polarization and thickness of ferroelectrics and AlGaN can increase the density of 2DEG..3. As to AlGaN/GaN/ ferroelectrics structure, we also detail stady polarization affect density of 2DEG and find that this structure can form double channel, carrier density can increase two times. The GaN on ferroelectrics can increase carrier mobility. It is can be used to high speed and high power device.4. As to the structure of strain AlGaN/GaN, we analysis the 2DEG of interface on the condition of strain. 1Gpa single pressure can increase the 2DEG density of AlGaN/GaN structure by 30%, 10Gpa can increase it to 2.4 times, and describe the main reason is that strain increases the polarization of AlGaN.Secondly, we studied 2DEG mobility in the interface of GaN heterojunction by used scattering mechanism. As to the structure of AlGaN/GaN, we mainly considered eight scattering mechanisms including interface roughness scattering, ionized impurities, deformation potential acoustic phonon scattering, piezoelectric scattering, polar optical phonon scattering , dislocation scattering, alloy disorder scattering and dipole scattering. At low or high temperature we analyzed that each scattering and material physical parameters influence the mobility of 2DEG..1. As to structure of strian GaN/BTO, we also studied the mobility of 2DEG affected by some material physical parameters in the condition of strain. The mobility decrease with increaing of interface roughness, dislocation density and electron effect qulity and it increase with increasing of polar optical phonon energy and high- frequency dielectric constant.2. We also stadied that dipole scattering affect the mobility and find Polarization effect affacts mobility only by 1%, and tensile strain can increase the mobility of 2DEG..