Influence Of Optical Phonons On The Electronic Mobility In A Strained Wurtzite AlN/GaN Heterojunction Under Hydrostatic Pressure

A variational method,combined with solving the force balance equation is adopted to investigate the biaxial strain and hydrostatic pressure influence on the electronic mobility in a strained wurtzite AlN/GaN heterojunction within the temperature range dominated by optical-phonon scattering.A realistic heterojunction potential model,which includes the influence of energy band bending and finite potential barrier,and the tunneling effect of electrons are considered to obtain the electronic mobility influenced by each branch of the optical phonon modes(including half-space(HS) optical phonons and interface optical(IF) phonons) as functions of electronic density and temperature.The results show that the electronic mobility decreases with hydrostatic pressure increasing when the electronic density varies from 1.0×10¹²/cm² to 6.5×10¹²/cm².The strain at interface of the heterojunction also reduces the electronic mobility,whereas the pressure influence becomes weaker when the biaxiaI strain is taken into account. The effect of strain and pressure becomes more obvious as temperature increases from 250K to 600K.The mobility increases firstly,and then decreases significantly, whereas the biaxial strain and hydrostatic pressure reduce this trend as the electronic density increases at a given temperature(300K).The results also indicate that the scattering from the half space phonon modes in the channel side plays a dominant role for the mobility,whereas the scattering from interface phonons plays a more important role as the electronic density increases.The electronic mobility always decreases with increasing temperature,no matter whether the biaxial strain and hydrostatic pressure exist.