Ideal SiC Schottky Barrier Diodes Fabricated Using Refractory Metal Borides

We present results of n-type 4H-SiC Schottky barrier diodes fabricated using several refractory metal boride Schottky contacts deposited on SiC held at various temperatures. From the electrical properties determined by current-voltage measurements, diodes with contacts deposited on SiC substrates held at 600 $^{o}$C had average ideality factors in the range 1.04 -- 1.09 and Schottky barrier heights of 1.02 eV -- 1.14 eV; and these values remained unchanged after the diodes were annealed at 600 $^{o}$C for 20 min. Diodes with contacts deposited on substrates held at 20 $^{o}$C had much higher ideality factors which decreased only slightly after the annealing. The Rutherford backscattering spectroscopy spectra of these contacts revealed a systematic decrease in oxygen with increase in the deposition temperature. The improved electrical properties and thermal stability are attributed to the removal of oxygen from the boride/SiC interface during high temperature deposition.