ELECTRON-STIMULATED REDUCTION OF SAPPHIRE STUDIED BY ELECTRON-ENERGY-LOSS AND AUGER SPECTROSCOPIES

Electron irradiation may change the surface composition of solids by e lectron stimulated processes. In the present work the effect of 1 keV electron irradiation on the near surface composition of sapphire was s tudied. The use of the whole range of the electron spectrum produced b y 1 keV primary electrons has provided a detailed picture of the varia tion with depth and electron dose of the surface and near surface of e lectron irradiated alpha-Al2O3(1000). Electron irradiation doses were in the range of 0.7 C/cm(2) to 26 C/cm(2). After a dose of about 1 C/c m(2) sufficiently large clusters of aluminum were produced to allow th e generation of the AI(LVV) 67 eV Auger peak, while after about 8 C/cm (2) the collective excitation surface and bulk plasmons were generated . An equilibrium in the composition of the first nanometer depth of th e surface is reached after a dose of about 6 C/cm(2), with similar to 50% of the aluminum in alumina being reduced to the metallic form. Aft er a dose of about 13 C/cm(2), the composition of the first 2 nm reach es equilibrium, while deeper alumina continues to be reduced.