Space charge on silicon oxide doped with boron and phosphorous: an XPS and AES study

The surface potential on silicon oxide caused by X-ray and electron beam irradiation was investigated. Thermal and anodic silicon oxides were compared with chemical vapor deposited silicon oxide doped with boron and phosphorous, borosilicate and borophosphosilicate glasses. The shift of AES peaks due to the potential gradient across the oxide layer were measured. For this purpose the C KLL Auger transition and C 1s core level peaks are registered as a function of time. Thus, the dependence of the rate of trapping on the electron energy and time was examined. After electron irradiation the trap states into the oxide are occupied with positive charge. The shift toward higher binding energies is correlated with the population of the impurity energy levels.