Two-dimensional particle modeling of submicrometer ZnO MESFET based on an ensemble Monte Carlo calculation including five-valley band structure model

Abstract

A Monte Carlo method has been developed for the study of electron transport properties in ZnO<br><br>MESFET for high field, using a five-valley conduction band model. The effects of upper valleys on the<br><br>characteristics of ZnO MESFETs have been investigated. The following scattering mechanisms, that is<br><br>impurity, polar optical phonon, acoustic phonon, alloy and piezoelectric are included in the calculation.<br><br>Ionized impurity scattering has been treated beyond the born approximation using the phase-shift<br><br>analysis. The simulation results show that on the drain side of the gate region, hot electrons attained<br><br>enough energy to be scattered into the upper satellite conduction valleys. Approximately 17% of the<br><br>electrons occupy the higher valleys (mainly U and M valley). The simulated device geometries and<br><br>doping are matched to the nominal parameters described for the experimental structures as closely as<br><br>possible, and the predicted drain current and other electrical characteristics for the simulated device<br><br>including upper valleys show much closer agreement with the available experimental data.