Absolute Reference Energy to Realign the Band-edges of Inorganic Semiconductors Using First-principles Calculations

TL;DR

This paper introduces a first-principles method to accurately determine the absolute energy reference for inorganic semiconductors, enabling better alignment of their band edges with experimental data for optoelectronic applications.

Contribution

A new theoretical approach using density functional theory to calculate absolute band-edge energies relative to a vacuum reference for inorganic semiconductors.

Findings

Predicted band-edges closely match experimental flat-band measurements.

Estimated mean absolute error of ~0.17 eV across eleven semiconductors.

Method improves the accuracy of band alignment predictions in first-principles calculations.

Abstract

The challenge of finding an absolute reference energy from first-principles simulations to realigning semiconductor's valence band-top and conduction band-bottom, a theoretical methodology is proposed based on plane-wave calculations as implemented within state-of-art density functional theory. We have studied some of inorganic binary semiconductors, including both oxides and non-oxides, as for example rutile- and anatase TiO2, wurtzite ZnO, rutile SnO2, blende phase of GaP, GaAs, InP, ZnTe, CdS, CdSe, and SiC, those are well known and qualitatively important for photoelectrochemical, optoelectronic device applications in their standalone and/or heterostructure morphologies. The calculated band-edges of these well known semiconductors are realigned with respect to our proposed absolute vacuum reference energy, which is defined with our proposed corrections and compared to their available experimental values from flat-band measurement. The prediction is reasonably well agreed with known experimental flat-band measured data. Our estimated mean absolute error bar for these set of eleven compounds is ~ 0.17 eV, closer to the known experimental limit 0.10-0.20 eV.