Transport Mechanisms in Focused Ion Beam Assisted Ohmic Contacts to p-Type 6H-SiC

Abstract

ABSTRACTThe current transport mechanism in non-annealed Ohmic contact metallizations on p-type 6H-SiC formed by using focused ion beam (FIB) surface-modification and direct-write metal deposition is reported, and the properties of such focused ion beam assisted non-annealed contacts are discussed. The process uses a Ga focused ion beam to modify the surface of the semiconductor with different doses, and then introduces an organometallic compound in the Ga ion beam, to effect the direct-write deposition of a metal on the modified surface. Contact resistance measurements by the transmission line method produced values in the low 10-4 Ω cm2 range for surface-modified and direct-write Pt and W non-annealed contacts, and mid 10-5 Ω cm2 range for surface-modified and pulse laser deposited TiN contacts. The current transport mechanism of these contacts was examined and found to proceed mainly by tunneling through the metal-modified-semiconductor interface layer.