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

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) Phi(ap) 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 Phi(ap) 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. (Phi) over bar (b) and A(*) as 1.71 eV, and 156.3 A/cm(2) K-2, respectively, have been calculated from a modified ln(I-0/T-2)-q(2)sigma(2)(s)/2k(2)T(2) 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/cm(2) K-2 is in close agreement with 146 A/cm(2) K-2 known for 4H-nSiC. (C) 2007 American Institute of Physics.