Surface modification of B-doped diamond films by GaS

Thin GaS films deposited on B-doped diamond (as-grown) and on oxygen-annealed B-doped diamond (O-ann.) films grown by plasma-assisted chemical vapor deposition (CVD) on p+-type Si(001) substrate have been characterized by Auger electron spectroscopy (AES), low-energy electron-loss spectroscopy (LEELS), and X-ray photoemission spectroscopy (XPS). The thermal evaporation of GaS single crystal is used for the deposition. At low primary electron energies (E-p less than or equal to 200 eV), the loss spectra are dominated by surface-related structures, and oxygen anneal removes the damaged surface layers of as-grown films. At high E-p (500 eV), surface- and bulk-plasmon peaks of diamond are observed to be dominant in the LEELS spectra for both as-grown and O-ann. films. After the deposition of GaS, some new loss peaks due to GaS appeared in the LEELS spectra for both as-grown and O-ann. films. XPS spectra indicate upward band bending due to GaS deposition compared to that of O-ann. films and slightly downward band bending compared to that of as-grown films.