OXIDE THICKNESS DEPENDENCE OF ENERGY SHIFTS IN THE SI 2P LEVELS FOR THE SIO2 SI STRUCTURE, AND ITS ELIMINATION BY A PALLADIUM OVERLAYER/

The energy difference between the oxide and substrate Si 2p peaks for silicon oxide/Si structures increases with the oxide thickness. The de pendence of the energy shift on the oxide thickness almost disappears with the deposition of a thin palladium overlayer, because of the avoi dance of the surface charging effect due to photoemission and because of the nearly constant energy shift resulting from extra atomic relaxa tion. The true chemical shift of silicon oxide layers thicker than 2 n m is determined to be similar to 3.8 eV. For the thickness dependence of the oxide Si 2p energy, the extra atomic relaxation and charging ef fect are dominant for oxide layers thinner than similar to 2 nm and th icker than similar to 4 nm, respectively. In the intermediate thicknes s region, both the effects are important. (C) 1998 American Institute of Physics.