Ab initio calculation of valley splitting in monolayer \delta-doped phosphorus in silicon

TL;DR

This paper develops and compares computational models to accurately calculate valley splitting in monolayer phosphorus delta-doped silicon, revealing previous overestimations by over 50%.

Contribution

It introduces a localized basis function approach that extends ab initio calculations beyond previous limitations, improving accuracy in valley splitting predictions.

Findings

Localized basis methods agree with plane-wave results

Previous ab initio estimates overestimated valley splitting by >50%

New models enable better design of quantum devices

Abstract

The differences in energy between electronic bands due to valley splitting are of paramount importance in interpreting transport spectroscopy experiments on state-of-the-art quantum devices defined by scanning tunneling microscope lithography. We develop a plane-wave density functional theory description of these systems which is size-limited due to computational tractability. We then develop a less resource-intensive alternative via localized basis functions, retaining the physics of the plane-wave description, and extend this model beyond the capability of plane-wave methods to determine the ab initio valley splitting of well-isolated \delta-layers. In obtaining agreement between plane-wave and delocalized methods, we show that the valley splitting has been overestimated in previous ab initio calculations by more than 50%.