Fermi level pinning and Schottky barrier characteristics on reactively ion etched 4H-SiC

The effects of reactively ion etching 4H-SiC epilayers in a CHF3/O-2 gas mixture on the properties of Pt, Ni, and Ti Schottky barriers subsequently deposited on the etched surfaces are investigated using forward and reverse current-voltage (I-V) and capacitance-voltage (C-V) measurements. Pronounced Fermi level pinning is present on the etched surfaces, and the forward I-V characteristics become anomalous. Average C-V barrier heights are 1.65, 1.44, and 0.81 V for Pt, Ni, and Ti on unetched material, respectively; and 1.42, 1.40, and 1.29 V, respectively, on etched material without annealing. The I-V characteristics are more uniform on etched material, and reverse leakage can be made acceptably low with suitable annealing for all three metals on etched material.