velocity-field characteristics of MgxZn1-xO/ZnO heterostructures

Abstract

In this work, the electron transport in MgxZn1−xO/ZnO heterostructures at room temperature is simulated by the ensemble Monte Carlo (EMC) method. Electron scatterings including deformed acoustic phonon (DAC), piezoelectric acoustic phonon (PAP), polar optical phonon (POP), interface roughness (IFR), dislocation (DIS), electron escape (ESC) and capture (CPR) by optical phonon, and random alloy (RAS), are considered in EMC. Electron drift velocities in MgxZn1−xO/ZnO heterostructures with various Mg composition x (0.1 ~ 0.3) are calculated at electric fields up to 25kV/cm. We find that there is no obvious velocity saturation occuring in the range of the electric field considered. The results show that ESC scattering is one of the main physical mechanisms that limit the drift velocity. On the other hand, it is found that the competition between IFR and intersubband POP scatterings plays an important role in the change of electron drift velocity with the increasing Mg compositions.