Electrical Characterizations of Hydrogenated 4H-SiC Epitaxial Samples

Abstract

4H-SiC epitaxial layers were hydrogenated by means of plasma treatment and annealing, aiming at passivating the surface by forming bonds with Si atoms. Ni/SiC Schottky contacts were processed, and investigated by electrical methods (I-V-T, C-V-T, EBIC, DLTS). The annealings were performed at two different temperatures (300°C and 400°C) in H2 ambient. The Inductively Coupled Plasma (ICP) treatment was effected before and after the Schottky contact metallization, and two integrated hydrogen doses were imposed for the same low energy (500 eV/atom). Two deep levels were detected in the gap of the sample hydrogenated at the highest dose before contact deposition, similar to the double defect RD1/2 associated to the vacancy pair VSi-VC. No deep level was found on other plasma-hydrogenated samples, which electrical characteristics are the same than for virgin SiC. A slight improvement of electrical parameters (lowering of ideality factor, increasing of minority carrier diffusion length, better switching behaviour) was only measured on the sample annealed at 400°C.