Realistic Tight Binding Model for the Electronic Structure of II-VI Semiconductors

TL;DR

This paper develops a realistic tight binding model for II-VI semiconductors that accurately captures their electronic structure using a minimal $sp^3d^5$ basis, emphasizing transferability and the importance of anion-anion interactions.

Contribution

It introduces a minimal, parameterized tight binding model for II-VI semiconductors that includes anion-anion interactions, improving accuracy without fictitious orbitals.

Findings

Nearest-neighbor $sp^3d^5$ model suffices for electronic structure

Hopping parameters follow Harrison's scaling law

Anion-anion interactions are necessary for subtle bonding features

Abstract

We analyze the electronic structure of group II-VI semiconductors obtained within LMTO approach in order to arrive at a realistic and minimal tight binding model, parameterized to provide an accurate description of both valence and conduction bands. It is shown that a nearest-neighbor $sp^3d^5$ model is fairly sufficient to describe to a large extent the electronic structure of these systems over a wide energy range, obviating the use of any fictitious $s^*$ orbital. The obtained hopping parameters obey the universal scaling law proposed by Harrison, ensuring transferability to other systems. Furthermore, we show that certain subtle features in the bonding of these compounds require the inclusion of anion-anion interactions in addition to the nearest-neighbor cation-anion interactions.