Surface preparation for Schottky metal - 4H-SiC contacts formed on plasma-etched SiC

Silicon-carbide-based devices frequently require a Schottky gate to be deposited on a plasma-etched surface. This paper considers the effectiveness of nine different pre-metallization surface preparation procedures in removing the etch damage. The surfaces were assessed by x-ray photoelectron spectroscopy and by current-voltage measurement of nickel Schottky diodes formed on both reactive-ion-etched and non-reactive-ion-etched silicon face 4H-SiC. The treatments included simple UV-ozone and solvent cleans, oxygen plasma, deposited oxide and thermal oxidation. It was confirmed that the only process which removed all traces of surface contamination and etch damage, producing ideal Schottky diodes, was sacrificial oxidation.