Thermal stability of Ru, Pd and Al Schottky contacts to p-type 6H-SiC

摘要

In this paper, a comparative study of the thermal stability of Ru, Pd and to a lesser extent Al Schottky contacts to p-type 6H-SiC and the influence of a hydrogen plasma treatment on these systems is presented. Ohmic contacts were prepared by thermally evaporating Al (180 nm) followed by Ti (50 nm) on the back surface of the SiC. Schottky contacts were subsequently formed on the polished top surface by evaporating ～0.8 mm diameter dots, 40 nm in thickness, through a metal contact mask. Isochronal (15 min) anneals revealed a general improvement in the SBD quality for temperatures up to 400℃ in the case of Ru and 300℃ for Pd, with progressive deterioration in the quality above these temperatures. Above 450℃ the Ru Schottky contacts became unusable whereas Pd was still functioning at 600℃. In contrast Al SBDs showed inferior thermal stability.