COMPARISON OF SiC AND ZnO FIELD EFFECT TRANSISTORS FOR HIGH POWER APPLICATIONS

Abstract

An ensemble Monte Carlo method is used to compare the potentialities of SiC and ZnO materials for field effect transistors. First, bulk material electron transport properties are compared and then the operation of MESFETs made from them are investigated. The simulated device geometries and doping are matched to the nominal parameters described for the experimental structures as closely as possible. Simulations of SiC MESFETs of lengths 2, 2.6 and 3.2 μm have been carried out and compared these results with those on ZnO MESFETs of the same dimensions. The direct current IV characteristics of the two materials were found to be similar, though the ZnO characteristics were on the whole superior, reaching their operating point at higher drain voltages and possessing higher gains. However, oscillations in the drain current caused by changes in drain voltage in the ZnO devices were not present to the same degree in the SiC devices. This difference is caused partially by the onset of the negative differential regime in SiC at a higher electric field than in ZnO but the primary cause is the longer ballistic transport times in SiC . This suggests that ZnO MESFETs may prove to have superior frequency response characteristics than SiC MESFETs.