Calculation of the mobility in Al2O3/GaN electron channel: Effect of p-doping and comparison with experiments

The low field electron mobility of Al2O3/GaN channel is calculated using a semi-classical framework. The aim is to obtain the mobility as a function of the electron sheet density and the temperature, with different p-doping conditions in GaN, and to compare it with our measurements on various samples. The scattering with bulk and surface phonons is taken into account. Scattering with dopants, interface charges, neutral impurities and interface roughness is also included in an attempt to account for experimental observations. We found that, when bringing p-dopants closer to the Al2O3/GaN interface, the mobility decreases mainly because the electron channel is more confined and located closer to Al2O3, thereby enhancing scattering mechanisms located near the Al2O3/GaN interface. Our results suggest that most of transport limitations come from Al2O3 oxide.