Theoretical investigation of the valence-band offset between Si(001) and SiO₂

The valence band offset at device quality interfaces between Si(001) and SEO₂ are investigated using local density functional electronic structure calculations. Several model interfaces have been examined. One includes a relaxed amorphous oxide and several hundred atoms. Combining the results of several calculations, one can draw the following conclusions regarding band offset formation. Reduced oxide strain within an amorphous oxide results in a small reduction in the valence band offset. The electrostatic dipole is important while the actual sub-oxide distribution is found to be a minor effect. Also, hydrogen and other defects normally are insignificant. However, the many body corrections to the local density single particle band edges are significant. Finally, the overall theoretical valence band offset is found to be 4.2 ± 0.3 eV. The experimental band offset results are re-examined in the context of these calculations.