Wannier-functions characterization of floating bonds in a-Si

TL;DR

This paper uses Wannier functions and density-functional calculations to analyze the electronic structure of over-coordinated defects in amorphous silicon, revealing delocalized states and highly polarizable bonds.

Contribution

It introduces a Wannier-function based approach to characterize the electronic properties of defects in amorphous silicon, linking topology and electronic behavior.

Findings

Five-fold coordinated defects produce delocalized electronic states.

Defective atoms exhibit high Born effective charges.

Defects lead to highly polarizable bonds.

Abstract

We investigate the electronic structure of over-coordinated defects in amorphous silicon via density-functional total-energy calculations, with the aim of understanding the relationship between topological and electronic properties on a microscopic scale. Maximally-localized Wannier functions are computed in order to characterize the bonding and the electronic properties of these defects. The five-fold coordination defects give rise to delocalized states extending over several nearest neighbors, and therefore to very polarizable bonds and anomalously high Born effective charges for the defective atoms.