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Structural Simplicity as a Restraint on the Structure of Amorphous Silicon

Accepted version
Peer-reviewed

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Authors

Cliffe, MJ 
Bartók, AP 
Kerber, RN 
Grey, CP 

Abstract

Understanding the structural origins of the properties of amorphous materials remains one of the most important challenges in structural science. In this study we demonstrate that local ‘structural simplicity’, embodied by the degree to which atomic environments within a material are similar to each other, is powerful concept for rationalising the structure of canonical amorphous material amorphous silicon (a-Si). We show, by restraining a reverse Monte Carlo refinement against pair distribution function (PDF) data to be simpler, that the simplest model consistent with the PDF is a continuous random network (CRN). A further effect of producing a simple model of a-Si is the generation of a (pseudo)gap in the electronic density of states, suggesting that structural ho- mogeneity drives electronic homogeneity. That this method produces models of a-Si that approach the state-of-the-art without the need for chemically specific restraints (beyond the assumption of homogeneity) suggests that simplicity-based refinement approaches may allow experiment-driven structural modelling techniques to be developed for the wide variety of amorphous semiconductors with strong local order.

Description

Keywords

cond-mat.mtrl-sci, cond-mat.mtrl-sci

Journal Title

Physical Review B - Condensed Matter and Materials Physics

Conference Name

Journal ISSN

2469-9950
2469-9969

Volume Title

95

Publisher

APS
Sponsorship
Engineering and Physical Sciences Research Council (EP/K030132/1)
Engineering and Physical Sciences Research Council (EP/K014560/1)
Engineering and Physical Sciences Research Council (EP/P022596/1)
Sidney Sussex College, Cambridge to M.J.C.; EPSRC to C.P.G. and R.P.K. under Grant No. EP/K030132/1 EPSRC (EP/G004528/2) and ERC (Grant Ref: 279705) to M.J.C and A.L.G.. A.P.B. was supported by a Leverhulme Early Career Fellowship with joint funding from the Isaac Newton Trust. Via our membership of the UK’s HEC Materials Chemistry Consortium, which is funded by the EPSRC (EP/L000202), this work used the ARCHER UK National Supercomputing Service (http://archer.ac.uk).