Numerical simulation of field effect transistors in 4H and 6H-SiC

Silicon Carbide is a very interesting semiconductor material for high temperature, high frequency, and high power applications. The main reasons are its high saturation velocity, large thermal conductivity, high Schottky barriers, and high breakdown voltages. High quality 4H-SiC and 6H-SiC polytype substrates and epitaxial layers are commercially available today. An additional advantage of SiC is the native oxide that allows fabrication of MOS devices. A large effort has been devoted towards the development of high performance devices in SiC. The largest success has been for unipolar devices like Schottky diodes and different kinds of MESFETs. MOSFETs have also been fabricated in both 4H- and 6H-SiC. Unfortunately, the MOSFET performance was found to be much worse than expected, due to a very low surface mobility. Nevertheless, the technology developed is very interesting and includes possible large scale integration of digital circuits operating at very high temperatures. In this work we present numerical simulations of the device performance of different Field Effect Transistors (FETs). Both full band Monte Carlo simulations and macroscopic modeling using the drift-diffusion approach have been utilized in this work. The Monte Carlo simulations have been used to extract transport parameters and to evaluate the macroscopic models in a device configuration.