Core level photoelectron spectroscopy studies of a √7 × √7 R19° reconstructed Au/4H-SiC(0001¯) surface

A study of surface and interface properties of thin Au layers deposited on SiC(0001¯) surfaces is reported. Two reconstructions were prepared, a Si-rich 2 × 2 and a C-rich 3 × 3 surface, before Au deposition and subsequent annealing at different temperatures. For the Si-rich 2 × 2 surface a stable √7 × √7 R19° reconstruction is obtained after Au deposition and annealing at temperatures between 400 and 850 °C. On this surface two surface shifted Si2p components are revealed and the Au4f spectra clearly indicate silicide formation. The variations in relative intensity for the different core level components with electron emission angle suggest: -formation of an ordered silicide layer on the surface, -excess Au (“bulk Au”) to form a layer underneath the ordered silicide, -and silicide formation also at the interface between “bulk Au” and SiC. The “bulk Au” component is found to decrease rapidly with annealing temperature. This decrease is due to Au diffusion into the SiC sample as confirmed by annealing at similar temperatures of Au films deposited onto deliberately oxidized SiC(0001¯) surfaces. For the C-rich 3 × 3 surface the evolution of the core level spectra after Au deposition and annealing is shown to be distinctly different than for the Si-rich 2 × 2 and no new stable reconstruction is observed.