Monte Carlo Investigation Of High-Field Electron Transport Characteristics In ZnMgO/ZnO Heterostructures

In recent years, based on the two-dimensional electron gas ?2DEG?, ZnMgO/ZnO hetero structures with high quantum efficiency have drawn a great deal of interest and are considered to be the perfect materials for photoelectric detectors devices because of their excellent electrical and optical properties. But it is limited to the material and characteristics of relevant materials such as scattering mechanisms and high-field transport characteristics are still not ideal. So it is necessary to do a further study on the transport properties of ZnMgO/ZnO hetero structures 2DEG. According to the band structures calculated by first principles for ZnO and Zn_1-xMg_xO, effect of quantization of the energy levels and different kinds scattering mechanisms, the ensemble Monte Carlo model for high-field electron transport characteristics in ZnMgO/ZnO heterostructures is developed, then the steady-state and transient high-field electron transport characteristics are investigated in-depth. The main studies and conclusive results are as follows:1. Based on the band structures for ZnO and Zn_1-xMg_xO and relevant parameters calculated by first principles, wave functions and effect of quantization of the energy levels describing the subband structure are achieved to determine the two-dimensional scattering rates by solving the Schrodinger and Poisson equations self-consistently. The ensemble Monte Carlo model for investigating electron transport characteristics in ZnMgO/ZnO heterostructures is established. The three scattering mechanisms: interface roughness scattering, alloy scattering and dislocation scattering are investigated, which of their scattering rates for intrasubband and intersubband with the increasing energy are obtained. Besides, the effects of different density of dislocation and Mg compositions on the 2DEG steady-state and transient-state transport are given.2. Considering the effect of quantization of the energy levels and different scattering mechanisms and based on the established ensemble Monte Carlo model for ZnMgO/ZnO heterostructures transport characteristics, the dependence of low-field electron mobility as a function of temperature is presented and the good agreement between the simulated low-field mobility and the reported experimental results confirms the effectiveness of our simulations. Furthermore, the steady-state and transient-state characteristics at high field and the evolution of electron occupancy with time for different applied electric fields are also studied. In addition, the effects of negative differential mobility and velocity overshoot are observed and discussed.This research is of good help for ZnMgO/ZnO heterostructure photoelectric devices design and fabrication.