Electrical characteristics modeling of large area boron: compensated 6H-SiC pn structures

Abstract

New models for the high frequency capacitance–voltage, C( V) and forward current–voltage, I F( V F) characteristics of a large area 6H–SiC boron compensated pn junction have been developed and implemented in an optimal parameter extraction program. The C( V) model and SIMS measurements confirm the presence of two type regions ( p − and n −) in the quasi-intrinsic layer induced by boron doping. The extracted values of the net doping of these zones (6−10×10 12 cm −3) are in good agreement with previously reported data. In contrast, the thickness of the quasi-intrinsic layer, about twice the epilayer width, proves the expansion of the quasi-intrinsic region in the substrate. The I F( V F) modeling includes a square law dependence of the forward current on V F, at high injection level. For the first time in the literature, saturation currents of SiC pn diodes is reported. The extracted saturation currents increase linearly with area, evidencing the beneficial effect of boron diffusion for obtaining predictable large area devices. The temperature behavior is also investigated. At high temperatures, the boron compensation effect is reduced.