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Inert gas bubble formation in magnetron sputtered thin-film CdTe solar cells

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journal contribution
posted on 10.11.2020, 11:20 by Peter Hatton, Ali AbbasAli Abbas, Piotr Kaminski, Sibel Yilmaz, Michael Watts, Michael WallsMichael Walls, Pooja GoddardPooja Goddard, Roger SmithRoger Smith
© 2020 The Authors. Cadmium telluride (CdTe) solar cells are deposited in current production using evaporation-based tech- niques. Fabricating CdTe solar cells using magnetron sputtering would have the advantage of being more cost-efficient. Here, we show that such deposition results in the incorporation of the magnetron working gas Ar, within the films. Post deposition processing with CdCl 2 improves cell efficiency and during which stacking faults are removed. The Ar then accumulates into clusters leading to the creation of voids and blisters on the surface. Using molecular dynamics, the penetration threshold energies are determined for both Ar and Xe, with CdTe in both zinc-blende and wurtzite phases. These calculations show that more Ar than Xe can penetrate into the growing film with most penetration across the (111) surface. The mechanisms and energy barriers for interstitial Ar and Xe diffusion in zinc-blende are determined. Barriers are reduced near existing clusters, increasing the probability of capture-based cluster growth. Barriers in wurtzite are higher with non-Arrhenius behaviour observed. This provides an explanation for the increase in the size of voids observed after stacking fault removal. Blister exfoliation was also modelled, showing the formation of shallow craters with a raised rim.

Funding

SUPERSOLAR Solar Energy Hub

Engineering and Physical Sciences Research Council

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History

School

  • Science
  • Mechanical, Electrical and Manufacturing Engineering

Department

  • Chemistry

Research Unit

  • Centre for Renewable Energy Systems Technology (CREST)

Published in

Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences

Volume

476

Issue

2239

Publisher

Royal Society

Version

VoR (Version of Record)

Rights holder

© The authors

Publisher statement

This is an Open Access Article. It is published by Royal Society under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

Acceptance date

24/06/2020

Publication date

2020-07-29

Copyright date

2020

ISSN

1364-5021

eISSN

1471-2946

Language

en

Depositor

Prof Michael Walls Deposit date: 9 November 2020

Article number

20200056