Electron transport properties of gallium nitride for microscopic power device modelling

The design of power GaN devices has to take into account the impact of temperature on device materials due to highly dissipated power and a consequent large self-heating. The accurate knowledge of transport properties as a function of the lattice temperature is essential in order to make a good thermal management to optimise the device performance. In this paper, accurate expressions describing the main transport properties as function of temperature and electric field for wurtzite GaN have been extracted starting from Monte Carlo simulations and then using a genetic algorithm. In particular, these expressions take into account the abrupt change in electron velocity slope at a low electric field (∼20 kV/cm). Using the same methodology, we have determined the temperature dependence of other physical parameters such as the low field mobility, saturation velocity, critical electric field and the corresponding peak velocity in a temperature range of 300 K - 700 K. The results show a very good agreement between the theoretical and experimental values.