Monte Carlo simulation of vertical MESFETs in 2H, 4H and 6H-SiC

The 4H-SiC static induction transistor (SIT) is a very competitive device f or high frequency and high power applications (3-6 GHz range). The large br eakdown voltage and the high thermal conductivity of 4H-SiC allow transisto rs with extremely high current density at high voltages. The SIT transistor shows better output power capabilities but the unity current-gain frequenc y is lower compared to a MESFET device. In this work we show, using a very accurate numerical model, that a compromise between the features given by t he SIT structure and the ordinary MESFET structure can be obtained using th e vertical MESFET structure. The device dimension has been selected very ag gressively to demonstrate the performance of an optimized technology. We al so present results from drift-diffusion simulations of devices, using trans port parameters obtained from the Monte Carlo simulation. The simulations i ndicate that 2H-SiC is superior to both 4H and 6H-SiC for vertical devices. For lateral devices, 2H-SiC is slightly faster compared to an identical 4H -SiC device. (C) 2001 Elsevier Science B.V. All rights reserved.