Ideal SiC Schottky barrier diodes fabricated using refractory metal borides

Abstract

Several refractory metal borides were used as Schottky contacts to fabricate n-type 4H-SiC Schottky diodes. The boride contacts were deposited on SiC substrates held at 20 and 600 °C. Contacts deposited on substrates held at 600 °C produced better diodes with smaller ideality factors from 1.05 to 1.10, barrier heights from 0.94 to 1.15 eV, smaller leakage current densities at a reverse bias of 15 V, and smaller specific on-resistances compared to contacts deposited on substrates held at 20 °C, and these values remained essentially unchanged after annealing at 600 °C for 20 min. The Rutherford backscattering spectroscopy spectra of one of these boride contacts revealed a systematic decrease in oxygen with an increase in the deposition temperature. The improved electrical properties and thermal stability make these boride contacts attractive for high power and high temperature device applications.