Accurate determination of the valence band edge in hard x-ray photoemission spectra using GW theory

TL;DR

This paper presents a new method combining experimental spectra and GW theory calculations to accurately determine the valence-band maximum in x-ray photoemission spectra, especially for complex materials.

Contribution

The authors introduce a novel approach that aligns experimental peaks with GW-based theoretical density of states to improve valence-band edge determination.

Findings

Method accurately determines valence-band maximum in complex spectra.

Verification with polarized photoemission confirms method's reliability.

Applicable to materials with mixed valence-band characters.

Abstract

We introduce a new method for determining accurate values of the valence-band maximum in x-ray photoemission spectra. Specifically, we align the sharpest peak in the valence-band region of the experimental spectrum with the corresponding feature of a theoretical valence-band density of states curve from ab initio GW theory calculations. This method is particularly useful for soft and hard x-ray photoemission studies of materials with a mixture of valence-band characters, where strong matrix element effects can render standard methods for extracting the valence-band maximum unreliable. We apply our method to hydrogen-terminated boron-doped diamond, which is a promising substrate material for novel solar cell devices. By carrying out photoemission experiments with variable light polarizations, we verify the accuracy of our analysis and the general validity of the method.