MONTE-CARLO STUDY OF ELECTRON-TRANSPORT IN SIC

Temperature- and electric field-dependent electron transport in 3C-, 4 H-, and 6H-SiC has been calculated by the Monte Carlo technique. Due t o the freezeout of deep donor levels the role of ionized impurity scat tering in 6H-SiC is suppressed and the role of phonon scattering is en hanced, compared to 3C- and 4H-SiC. There are indications of impurity band formation for impurity concentrations exceeding 10(19) cm(-3). It is found that ionized impurity scattering along with the deep donor i onization is responsible for the temperature dependence of mobility an isotropy ratio. Electron effective masses and electron-phonon coupling constants have been deduced from the comparison of Monte Carlo simula tion results with available experimental data on low-field electron mo bility. The extracted model parameters are used for high-held electron transport simulations. The calculated velocity-field dependencies agr ee with experimental results. The saturation velocities in all three p olytypes are close, but the transient velocity overshoot at high elect ric field steps is much more pronounced in 3C-SiC. (C) 1998 American I nstitute of Physics.