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

Abstract

The valence band spectra of ultrathin SiO 2 /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 SiO 2 is obtained by subtracting the bulk Si contribution from the measured spectrum. Thus the band alignment at ultrathin SiO 2 /Si interfaces has been determined to be 4.36±0.10 eV independent of oxide thickness between 1.8 and 3.7 nm.