p-Si/4H-SiC heterojunction diodes are realized by sputter-deposition of the Si top contact and subsequent post-deposition annealing at either 900 °C or 1000 °C. The high Schottky barrier height (SBH) of this junction architecture of around 1.65 V is ideal to analyze SBH inhomogeneities present in most Schottky- and heterojunctions. Current-voltage-temperature (IVT) and capacitance-voltage-temperature (CVT) measurements are conducted in a wide temperature range from 60 K up to 460 K while applying standard techniques for SBH extraction. Strong deviations from ideal IV characteristics are present especially at lowest temperatures when assuming a homogenous SBH. Additionally, the extracted SBHs at low temperatures differ a lot between the two methods, indicating the presence of low barrier conduction paths. The presence of at least two distinct SBH inhomogeneities is found, which are labeled as ‘intrinsic’ and ‘extrinsic’. Next, the Tung model was applied to fit the measured IVT data using a discretized Gaussian distribution of patch parameters to account for spreading resistance effects. By using multiple Gaussian distributions, excellent fitting results were achieved, giving the density values of the different patches and a background barrier height from the IVT data, which are in excellent agreement with the CVT data over a wide temperature range of 400 K.

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In this paper, four widely used interface trap characterization methods based on quasistatic and high-frequency capacitance–voltage (CV) and conductance–frequency (Gω) measurements are evaluated at thermally oxidized 4H-SiC metal oxide semiconductor structures. To cover a wide range of defect levels in a wide bandgap semiconductor, the CV and Gω measurements are conducted at temperatures ranging from 150 to 600 K. Interface trap densities Dit are extracted using the high-frequency Terman method, the low frequency capacitance method, the high-low frequency method, and the conductance method. A very good agreement between the different methods is observed in restricted energy ranges. The use of the conductance method allowed for the determination of defect states in an energy range of almost 800 meV. A strong hysteresis of bidirectional CV curves is observed at different temperatures and is used to estimate border trap densities. The presence of mobile charges in the oxide is found to be a limiting factor for high temperature CV measurements. Low temperature Gω measurements revealed a second conductance peak which is identified as the 100 meV nitrogen donor level.

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