Presentation Details
| Process Optimization of Sputtered ZnO-Based Electron-Selective Contact for Non-Epitaxial, Heterojunction InP Solar Cells Venkata S.A.Chaluvadi1, Toluwalase Agoro1, Luksa Kujovic2, Adam M.Law2, Kieran Curson2, John M.Walls2, Louise C.Hirst1. 1University of Cambridge, Cambridge, United Kingdom.2Loughborough University, Loughborough, United Kingdom |
Abstract
Despite high specific power and superior radiation tolerance, III-V solar cells remain limited by the high cost and scalability constraints of epitaxial growth. By utilizing industry-scalable sputtering techniques, we investigate ZnO as an electron-selective contact (ESC) for non-epitaxial, heterojunction InP solar cells, with a focus on understanding and mitigating sputter-induced damage through process optimization. Using time-resolved photoluminescence correlated with device metrics, we identify oxygen partial pressure, deposition temperature, and substrate doping as key levers governing interface quality, carrier extraction, and optical losses. Optimization of ZnO sputtering conditions, utilizing an optimal oxygen partial pressure for intermediate oxygen vacancy formation, alongside room temperature ITO results in a low degradation factor in minority-carrier lifetime. Furthermore, reducing the acceptor doping concentration from 2 × 1018 cm-3 to 7 × 1016 cm-3 increases Jsc from 16.5 to 25.6 mA/cm2, boosting efficiency to 15.2%, consistent with enhanced diffusion length and reduced depletion region recombination. While significant sputtering damage still occurs, the introduction of the ZnO ESC improves end-of-processing carrier lifetimes by ~5x and results in a higher Voc of 786 mV, comparable to previous ALD-based results. This work demonstrates that sputtered ESCs can preserve the intrinsic advantages of InP when appropriately engineered, furthering an interesting pathway for high specific power, radiation tolerant InP photovoltaics without epitaxy.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.