Electron Transport Properties Of ?-(Al_xGa_1-x)₂O₃/?-Ga₂O₃ Heterojunction

Ga₂O₃ is an attractive wide-band gap semiconductor material.Because of its high breakdown field strength and ultra wide band gap,it is becoming a promising material for high-power switching electronic devices,photodetectors and solar blind ultraviolet detectors.Ga₂O₃has five crystal types,among whichβ-Ga₂O₃is the most stable and most studied phase,β-Ga₂O₃crystal structure has symmetrical center,but lacks any special properties,such as piezoelectric,ferroelectric and so on.In order to obtain a high density of two-dimensional electronic gas（2DEG）,it is necessary to dopingβ-(Al_xGa_1-x)₂O₃barrier layer and insert a very thin barrier layer,and at the same time,it is necessary to strictly control the growth parameters,mutant heterogeneous interface and sharp doping profile.Because there is a high mobility of two-dimensional electronic gas（2DEG）at the interface of the heterojunctions,so it 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-x)₂O₃/?-Ga₂O₃high electron mobility transistor（HEMT）.In this paper,the effect of?-(Al_xGa_1-x)₂O₃as a potential barrier on the electron transport properties of?-(Al_xGa_1-x)₂O₃/?-Ga₂O₃heterojunction is studied.The expressions of polarization charge density and two-dimensional electron gas（2DEG）concentration under electric neutrality are derived.Then some scattering theories are introduced.Finally,the effects of alloy disorder scattering,interface roughness scattering,polar optical phonon scattering and random dipole scattering on carrier mobility are calculated.In this paper,the structure and properties of?-(Al_xGa_1-x)₂O₃/?-Ga₂O₃heterojunction are introduced,and the calculation method of piezoelectric polarization and charge on the polarization surface is obtained by establishing?-(Al_xGa_1-x)₂O₃/?-Ga₂O₃heterojunction model.Then we can calculate the concentration of two-dimensional electronic gas（2DEG）based on the principle of electric neutrality.Then some scattering theories,including time-dependent perturbation theory,relaxation time approximation,Boltzmann transport equation,conductivity and mobility,are introduced.Finally,the effect of?-(Al_xGa_1-x)₂O₃barrier thickness and Al mole component on carrier mobility is studied by calculating carrier mobility under different scattering conditions.It is concluded that the main scattering mechanism limiting the carrier mobility in?-(Al_xGa_1-x)₂O₃/?-Ga₂O₃heterojunction is interface roughness scattering,and the disordered scattering of alloy has little effect on the carrier mobility.The relationship between the four kinds of scattering on the carrier mobility is as follows:Interface roughness scattering>polar optical phonon scattering>random dipole scattering>alloy disorder scattering.Calculation results show that the electron mobility of two-dimensional electron gas（2DEG）concentration,alloy disorder scattering,interface roughness scattering,polar optical phonon scattering and random dipole scattering are determined by the thickness of?-(Al_xGa_1-x)₂O₃barrier and Al mole composition.