Temperature dependence of electrical behaviour of inhomogeneous Ni/Au/4H–SiC Schottky diodes

Temperature dependence of electrical parameters of Ni/Au/4H–SiC Schottky diodes in a small temperature interval has been studied. Current–voltage characteristics were measured between 35 and 80 °C. I–V curves have not a linear part in semi-logarithmic plot which indicates barrier height inhomogeneity. We analyzed forward part of the I–V curves assuming Gaussian barrier height distribution and parallel connection of diode patches with different barrier heights. Using the least squares method we determined mean barrier height, standard deviation of the barrier height distribution and finally series resistance of the diode as a function of temperature. The extracted barrier height and standard deviation of the distribution decrease with increasing temperature. In contrary the series resistance of the diode increases with increasing temperature. As an interesting feature and a consequence of the series resistance increase with temperature a crossing of the I–V curves in practically the one point of the I–V curve has been observed. At this cross-point the current flowing through the diode is independent of the temperature.