Relative stability of zincblende and wurtzite structure in CdX(X = S, Se, Te) series - A NMTO study

TL;DR

This study uses NMTO-downfolding to analyze the stability of zincblende and wurtzite structures in CdS, CdSe, and CdTe, revealing how ionicity and covalency influence their preferred crystal symmetry.

Contribution

It provides a detailed NMTO-based analysis of the relative stability of ZB and WZ structures in CdX semiconductors, clarifying the role of ionicity and covalency.

Findings

CdS stabilizes in WZ due to high ionicity.

CdSe and CdTe favor ZB because of covalency.

NMTO Wannier functions illustrate bonding characteristics.

Abstract

Using NMTO-downfolding technique we have revisited the issue of relative stability between zincblende (ZB) and wurtzite (WZ) symmetries in case of CdS, CdSe and CdTe semiconductors. Our computed ionicity factors using accurate NMTO-downfolding successfully brings out the right trend within the CdX series - CdS being most ionic stabilizes in WZ symmetry while CdSe and CdTe being more covalent stabilizes in ZB symmetry. Our NMTO constructed Wannier functions corresponding to only valence bands provide a nice demonstration of this fact. The tendency towards ZB stability is governed by the covalency which prefers isotropic nature of the tetrahedral bonds.