Electron mobility in abrupt-interface and step-graded AlGaN/GaN Heterostructures

Abstract

Based on the ensemble Monte Carlo method, we present a comparative study of the electron mobility of two-dimensional electron gases (2DEGs) formed in AlGaN/GaN abrupt-interface heterostructures (ABHs) and step-graded heterostructures (SGHs) at room temperature. We find that the electron mobility in SGHs is obviously higher than that in ABHs. The dependence of electron mobilities on the AlGaN barrier thickness is found to have a close relationship with the dislocation scatterings of electrons. On the other hand, our calculated results show that the mobility difference between SGHs and ABHs generally increases with AlGaN barrier thickness, which means that SGHs with a thicker barrier layer play a more prominent role in obtaining high mobility, compared with ABH counterparts.