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 influence of strain and hydrostatic pressure on electronic mobility in a strained wurtzite AlN/GaN heterojunction by considering the scattering of optical-phonons in a temperature ranges from 250 to 600 K. The effects of conduction band bending and an interface barrier are also considered in our calculation. The results show that electronic mobility decreases with increasing hydrostatic pressure when the electronic density varies from 1.0 × 1012 to 6.5 × 1012 cm-2. The strain at the heterojunction interface also reduces the electronic mobility, whereas the pressure influence becomes weaker when strain is taken into account. The effect of strain and pressure becomes more obvious as temperature increases. The mobility first increases and then decreases significantly, whereas the strain and hydrostatic pressure reduce this trend as the electronic density increases at a given temperature （300 K）. The results also indicate that scattering from half space phonon modes in the channel side plays a dominant role in mobility.