Special features of formation and characteristics of Ni/21R-SiC Schottky diodes

Abstract

The Ni/n-21R-SiC(0001) and $$Ni/n - 21R - SiC(000\bar 1)$$ surface-barrier structures formed on 21R-SiC crystals doped to a concentration of (1–2)×1018 cm−3 and grown by the Lely method were investigated prior to and after rapid thermal annealing (RTA) in vacuum (10−2 Pa) in the temperature range of 450–1100°C. Using X-ray diffraction analysis and Auger analysis, it is shown that cubic NiSi2 and orthorhombic δ-Ni2Si and NiSi silicides coexist with pure Ni in starting samples. The RTA brings about a polymorphic transformation of these phases, which causes the transformation of a barrier contact to a rectifying one independently of the SiC face type, even at T≳600°C. The physicochemical mechanisms of degradation of these barrier structures are discussed.