The impact of alloy cluster scattering on low-temperature mobility of 2D electron gas in Zn1-xMgxO/ZnO heterostructures

Abstract

The influence of alloy cluster scattering on the electron transport properties in undoped Zn1-xMgxO/ZnO heterostructures was studied theoretically. Alloy cluster scattering is treated as an elastic scattering occurring between MgZnO clusters and electrons. The electron energies and wave functions are obtained to calculate the scattering rates of two-dimensional electron gas (2DEG) by solving the Schrödinger and Poisson equations self-consistently. The total low-temperature mobility is then calculated by using Matthiessen’s rule. It is found that the composition fluctuation of the Zn1-xMgxO barrier affects the mobility of electrons confined in the ZnO well via alloy cluster scattering. The electron mobility limited by alloy cluster scattering decreases with Mg composition fluctuation increased from 0.01 to 0.05. Furthermore, alloy cluster scattering is one of the dominant scattering mechanisms at low temperature. When alloy cluster scattering is taken into consideration, the simulated results are in better agreement with the experimental values for lower mobility samples with higher Mg composition. This work is useful for designing Zn1-xMgxO/ZnO heterostructure devices.