The chemical reactions and Schottky-barrier characteristics of W(200nm)/Si(0 to 2.5nm)/GaAs contacts when annealed at 800C were investigated. The Si interfacial layers and W films were sputter-deposited onto chemically etched GaAs substrates. The W/Si/GaAs diodes clearly exhibited the same Schottky-barrier characteristics as those of (WSi0.6)/GaAs diodes. By using secondary ion mass spectrometry, the Si layer was found to suppress Ga atom diffusion from GaAs substrates into W films during annealing (800C, 1h). A reduction in natively oxidized GaAs surfaces was also observed in the initial stages of Si layer deposition by X-ray photo-emission spectroscopy. These results suggested that the Si layer eliminated native oxides from GaAs surfaces, resulting in tungsten-silicide/GaAs intimate contact formation at the interface. The Si obstructed the diffusion paths of Ga atoms at W grain boundaries with W-Si-O ternary compounds.

Effects of Si Thin Interfacial Layer on W/GaAs Contacts. Y.Kuriyama, S.Ohfuji, J.Nagano: Journal of Applied Physics, 1987, 62[4], 1318-23