THE DEPOSITION OF A THIN AU FILM ON INSB(100)

The deposition of Au at room temperature onto InSb(100) has been studied by high resolution electron energy loss spectroscopy (HREELS), Auger electron spectroscopy (AES) and low energy electron diffraction (LEED). At low coverages (< 4 ML), the Au forms islands on the surface and there is significant local disruption of the InSb surface with intermixing at the interface. The InSb conduction band plasmon excitation is reduced in intensity but is still observable in the HREEL spectra. At higher coverages (> 4 ML), screening of the plasmon occurs due to the formation of a thin metallic film and AES results indicate significant segregation of Sb to the surface of the Au film. After annealing the Au-covered (approximately 10 ML) surface to 625 K, a c(4 X 4) structure is observed by LEED. HREEL spectra, recorded after the same treatment, show the re-appearance of the InSb conduction band plasmon. The results are consistent with the migration of the Au into the near-surface region of the InSb, the formation of a sub-surface In-Au alloy and an Sb-rich surface due to segregation.