Temperature-dependent behavior of Ni/4H-nSiC Schottky contacts

Abstract

The current-voltage (I-V) characteristics of Ni/4H-nSiC Schottky diodes have been measured in the temperature range of 180–300 K with a temperature step of 20 K. An experimental barrier height (BH) Φap value of about 1.32 eV was obtained for the Ni/4H-nSiC Schottky diode at the 300 K. A decrease in the experimental BH Φap and an increase in the ideality factor n with a decrease in temperature have been explained on the basis of a thermionic emission mechanism with Gaussian distribution of the barrier heights due to the BH inhomogeneities at the metal-semiconductor interface. Φ¯b and A* as 1.71 eV, and 156.3 A/cm2 K2, respectively, have been calculated from a modified ln(I0/T2)−q2σs2/2k2T2 vs 1/T plot using the temperature-dependent experimental I-V characteristics of the Ni/4H-nSiC contact. The Richardson constant value of 156.3 A/cm2 K2 is in close agreement with 146 A/cm2 K2 known for 4H-nSiC.