Abstract
Hydrogen retention properties of Li were investigated using a dc glow discharge apparatus with a heater for Li evapo ration. Hydrogen retention of Li after the evaporation was measured based upon a residual gas analysis. In addition, the recovery effects for hydrogen trapping of Li due to baking and He discharge cleaning were examined.
The hydrogen gas pressure largely decreased in the initial discharge stage and then the decreasing ratio became small with the discharge time. The initial decrease is due to the trapping of H+ and the hydrogen concentration becomes approximately unity in atomic ratio, H/Li, in the ion implantation depth. The slow trapping is presumed to be the diffusion of H into the bulk of Li film.
When the Li evaporation amount was small, both the decrease of hydrogen pressure and the desorption of H2O were observed. Since the oxide, Li2O, is partly formed, it is regarded that the reaction, Li2O+2H2→H2O+2LiH, took place.
After the hydrogen discharge for the Li film, the baking with 100°C or He discharge cleaning was conducted, and followed by again the hydrogen discharge was made. Compared with the case of He discharge cleaning, the hydrogen trapping was largely recovered in the case of such the baking.
