High frequency characteristics and modelling of p-type 6H-silicon carbide MOS structures

This paper presents the high frequency electrical characteristics and modelling of Al/SiO2/p-type 6H-SiC structures. The oxide was thermally grown under dry conditions. Capacitance and conductance vs bias and frequency measurements have been performed in daylight and exposing the capacitors to u.v. light. The experimental C-m-V-g and G(m)-V-g characteristics show hysteresis effects, which are more important when the samples are exposed to 254 nm u.v. light. This behaviour can be explained in terms of interface traps. The MOS structure modelling is based on an interface trap model in which the interface trap levels are considered to be continuously distributed in the SiC bandgap and only charge exchange between interface trap levels and the SiC bands is allowed. From this formulation and from the G(m)-f characteristics, the interface state density and the interface trap time constant have been determined. Copyright (C) 1996 Elsevier Science Ltd