Oxidation studies of hydrogenated amorphous silicon

Hydrogenated amorphous silicon surfaces, atomically clean and subsequently oxidized to up to 20 Å oxide thickness, were studied using AES and UPS. The oxidation was made in O₂ in the pressure range 10^?9 Torr to 5 atm and at 23 and 300°C. The oxidation rate at 23°C was found to be the same as that of crystalline silicon while at 300°C it was appreciably faster. Changes in the d $\text{N(E)}\text{dE}$ AES Si LVV line shape near 80 eV upon oxidation could be correlated to changes in the silicon-oxygen bonding level observed in UPS. The detailed line shape of the AES Si LVV transition indicates that at 300°C a more homogeneous oxide is produced than at 23°C.