Effect of the contact area on the electrical characteristics of the Ti/6H-SiC (n) Schottky diode

In this paper, we investigated three different sizes (1.6 x 1.6, 1.6 x 0.4 and 0.4 x 0.4 mm2) of Ti Schottky diodes on n-type 6H-SiC epitaxial layers using current-voltage-temperature I-V-T measurements. At room temperature, Schottky contacts I-V characteristics are influenced by the dimensions of the contact area, the bigger and medium diodes present near-ideal behavior following the thermionic emission current theory. However, the characteristics of the smaller diode are affected by the presence of two barrier heights, which can be identified as abnormal interface inhomogeneities. The basic Schottky diode parameters are extracted by the standard Least Mean Square LMS method, recalculated and explained by the thermionic emission current theory (TE) using the Newton-Raphson method. An exhaustive analysis was carried according to the temperature in a wide range 77-500 K which also shows a deviation from the ideality at lower temperatures, thus suggesting that an inhomogeneous barrier has indeed formed and this for all three contacts. The I-V-T analysis allowed us to evaluate the Richardson constant A* in the Ti/6H-SiC Schottky diode by applying the barrier height inhomogeneities correction with the Gaussian distribution. It was close to the theoretical value.