Monte Carlo analysis of electron relaxation process and transport property of wurtzite InN

Abstract

Both the electron relaxation process and the transport property of wurtzite InN have been investigated using an ensemble Monte Carlo method. The band structure of the classic three valleys model is adopted, and the anisotropy of the band structure by Herring-Volt transform is also taken into consideration. The peak velocity in the Γ-A direction (c-direction) is higher than that in the Γ-M direction (basal plane), and the onset of negative differential mobility (NDM) appears at relatively lower electric field. Both velocity transport and the energy relaxation process in three valleys have been investigated. It has been found that the electrons in the high valley also show obvious energy overshoot besides the total energy overshoot. Based on the correlation of the drift velocity and the average energy versus time in the lowest valley, it has been concluded that nonparabolicity of band structure impacts the velocity overshoot greatly. Further research shows that nonparabolicity also plays an important role in NDM at low electric field, whereas intervalley scattering becomes important to NDM at high electric field. The total average energy overshoot is mainly caused by the intervalley scattering. Finally, the velocity undershoot in wurtzite InN is observed by applying a pulse electric field on simulated electrons.