High Resolution Photoemission Investigation of the Si/SiO sub 2 Interface for Thin Oxides Prepared on Atomically Smooth Si Surfaces

High resolution synchrotron excited photoemission spectroscopy provides a sensitive tool for measuring the chemical state of Si atoms at the Si/SiO sub 2 interface. Previous studies have concentrated exclusively on oxide interfaces prepared on either chemically or thermally cleaned Si Substrates. Those studies indicate a transition region between crystalline Si(100) and stoichiometric SiO sub 2 which is approximately two monolayers thick with the primary contributions coming from Si atoms in the +2 and +3 oxidation states. Recent cross sectional TEM studies[1] of oxides prepared on atomically smooth MBE grown Si(100) surfaces indicated the presence of an atomically abrupt Si/SiO sub 2 interfaces which appear to be ordered. We present photoemission spectroscopy results which reveal these interfaces are far more abrupt than those previously observed.