Determination of Valence Band Alignment at Ultrathin SiO2/Si Interfaces by High-Resolution X-Ray Photoelectron Spectroscopy

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Abstract
The valence band spectra of ultrathin SiO2/Si interfaces have been measured by high-resolution X-ray photoelectron spectroscopy. The energy shifts found in the Si2p and O1s core-level peaks arising from the charging effect are carefully corrected and the valence band density of states for ultrathin SiO2 is obtained by subtracting the bulk Si contribution from the measured spectrum. Thus the band alignment at ultrathin SiO2/Si interfaces has been determined to be 4.36±0.10 eV independent of oxide thickness between 1.8 and 3.7 nm.