COMPARISON OF SiC AND ZnO FIELD EFFECT TRANSISTORSFOR HIGH POWER APPLICATIONS

摘要

An ensemble Monte Carlo method is used to compare the potentialities of SiC and ZnOmaterials for field effect transistors. First, bulk material electron transport propertiesare compared and then the operation of MESFETs made from them are investigated.The simulated device geometries and doping are matched to the nominal parametersdescribed for the experimental structures as closely as possible. Simulations of SiC MES-FETs of lengths 2, 2.6 and 3.2 μm have been carried out and compared these results withthose on ZnO MESFETs of the same dimensions. The direct current IV characteristicsof the two materials were found to be similar, though the ZnO characteristics were onthe whole superior, reaching their operating point at higher drain voltages and possess-ing higher gains. However, oscillations in the drain current caused by changes in drainvoltage in the ZnO devices were not present to the same degree in the SiC devices. Thisdifference is caused partially by the onset of the negative differential regime in SiC at ahigher electric field than in ZnO but the primary cause is the longer ballistic transporttimes in SiC. This suggests that ZnO MESFETs may prove to have superior frequencyresponse characteristics than SiC MESFETs.