Surface-Barrier Diodes on Silicon Carbide

Abstract

Metal—semiconductor Schottky barrier contacts on SiC have been made both by cleaving single crystals of SiC (6H and 15R polytype) in ultrahigh vacuum in a stream of evaporating metal, and by evaporating metal onto etched surfaces. Results of capacitance and photoresponse measurements on n‐type and p‐type samples are presented. The barrier height on n‐type samples is 1.45(±0.10) eV, independent of the work function of the metals (Au, Ag, Al). Nearly the same value is found for Al contacts on p‐type SiC. When Au contacts are used, the barriers on heavily doped p‐type crystals spread from 0.90–1.25 eV. The results for the purer n‐type samples show that the Fermi level at the interface is fixed by surface states at the middle of the energy gap.