Oxygen passivation and reactivation of interface states introduced during Schottky diode fabrication on bulk n-type 6H-SiC

Typical and deviant Au or Au-Ge Schottky diodes fabricated via thermal (resistive) metallization on bulk 6H-SiC are boiled in 17.8 M Omega deionized water. Boiling of the typical devices (shown elsewhere to contain the p1-, p1*-, p2-, p3-, p5-, and possibly the t1-related defects-where p5 and t1 are associated with a band of interface states) results in passivation of the interface states. Passivation is accompanied by a reduction in the measure of reverse leakage current associated with the devices. A process of elimination is shown to establish oxygen as the passivating species. Through annealing experiments significant reactivation of the passivated defects is shown to commence at some temperature between 350 and 400 degreesC beyond which reactivation is accelerated. It is shown that boiling deviant devices (additionally containing the unusual p4-related defect) in deionized water does not result in passivation. This finding is ascribed to the presence of an interfacial blocking layer peculiar to the deviant devices. (C) 2003 Elsevier B.V. All rights reserved.