Schottky barrier height and thermal stability of p-diamond (100) Schottky interfaces

Schottky interface properties of p-diamond (100) were investigated. Gold (Au), which is a representative noble metal, and tungsten carbide (WC), a carbide preformed metal, were selected as Schottky contact metals. When Au was used as the Schottky metal, Schottky properties were strongly related to the surface oxidation method. The Schottky barrier height was as high as > 2 eV. The distribution of the ideality factor became small when using the vacuum ultraviolet (VUV) light/ozone treatment for diamond surface oxidation, compared to the case of conventional wet-chemical oxidation treatment. However, for a WC Schottky contact, interface properties were insensitive to the surface oxidation method. This insensitivity was regarded as deriving from the formation of interfacial bonding between WC and diamond during metal deposition. Schottky barrier diodes (SBDs) prepared by the VUV light/ozone treatment showed good temperature stability with low reverse current of < 1 pA up to 550 K. Through heating at higher temperatures of > 600 K, the ideality factor of Au SBD increased and the Schottky barrier height changed greatly. Oxygen termination dissociation was inferred to occur at the Au/diamond Schottky interface. WC SBD had better thermal stability than Au SBD because the interface was stabilized by interfacial bonding.