Simulation of electron transport in (0001) and (11(2)over-bar0) 4H-SiC inversion layers

Monte Carlo simulations are used to investigate electron transport in the inversion layer of a 4H silicon carbide metal-oxide-semiconductor field-effect transistor (MOSFET). The electronic subband structure is solved self-consistently along with the perpendicular field at the semiconductor-oxide interface. Inversion channel scattering rates due to acoustic and polar optical phonons, ionized dopants, trapped charge, and interface roughness are considered. Transport within (0001) and (11 (2) over bar0 oriented inversion layers are compared. Simulations of the MOSFET low-field mobility, incorporating previously published experimental results for threshold voltages and charge densities, are found to agree well with experimental results. The mobility of the (11 (2) over bar0) channel is much larger (90 cm(2)/Vs) than that of the (0001) channel (<40 cm(2)/Vs) due to a reduction in interface states. Furthermore, the mobility has a temperature coefficient of approximately -3/2 for (11<(2)over bar>0) layers due to dominant phonon scattering and +1 for (0001) layers, where interface trap scattering dominates. Since the band structure is very similar, transport variations among the two crystal orientations are found to result largely from the enhanced interface trap density in the (0001)-oriented interfaces. (C) 2009 American Institute of Physics. [doi:10.1063/1.3212970]