Temperature dependence of the electron induced gas desorption yields on stainless steel, copper, and aluminum

Electron induced gas desorption yields from stainless steel, copper, and aluminum surfaces have been measured for electrons of 300 eV energy. The main gases desorbed were H-2, CH4, H2O, CO, and CO2. The effect of increasing the temperature on the gas desorption yields was measured and the only yields affected were those of H2O and H-2, while the others remained essentially constant. The dependence on the dose and the temperature using two identical samples was also measured and the yields were found to be proportional to the dose to the power-alpha, with alpha positive. No big differences with temperature were seen. The value of the exponent for H-2 is bigger than that expected for a diffusion model. The dependence with coverage and temperature was also analyzed, showing that the cleaning effect is quicker at higher temperatures, especially for H-2. A diffusion model for H-2 was applied to interpret the experimental results, showing that the model explains the results, if we consider that the H-2 concentration across the bulk of the material, decreases exponentially. (C) 1997 American Vacuum Society. [S0734-2101(97)00606-4].