Presentation Details
| Investigating Porous Silicon Buffer Layers as Compliant Layers for Cost-Effective Ge-on-Si Substrates in III-V Solar Cells (yes) Ella S.Supik1, 2, Stefanie Lawundy1, 2, Chia-Sheng Liu2, Charlotte Weiss2, Stefan Janz2, Andreas W.Bett1, 2. 1University Freiburg, Freiburg, Germany.2Fraunhofer Institute for Solar Energy Systems, Freiburg, Germany |
Abstract
The increasing demand for germanium, particularly in highly efficient III-V solar cells, requires the development of sustainable and cost-effective substrate solutions. Ge-on-Si substrates are explored as a promising alternative to conventional Ge wafers, aiming to reduce both weight and Ge consumption. However, the significant thermal and lattice mismatch between Ge and Si leads to high strain, elevated defect densities, and increased surface roughness in the epitaxial layer. Porous silicon (PorSi) is investigated as a potential buffer for Ge epitaxy. Varying porosities, thicknesses, and stacking sequences of PorSi are tested under different annealing conditions, both with and without Ge epitaxy. The resulting samples are characterized by analyzing key parameters such as lattice constants, crystalline quality, and structural changes to identify optimal parameters for developing compliant PorSi templates suitable for Ge and III-V solar cells. We find that Ge/LowT PorSi, despite its higher defect density, may offer a more viable option for further processing due to the anticipated higher elasticity and increased lattice constant towards Ge. In contrast, the significant flaking observed in Ge/HighT PorSi poses considerable risks for subsequent thermal processing and III-V epitaxy. These insights into the behavior of PorSi under different processing conditions provide a foundation for developing scalable and sustainable substrate solutions, ultimately contributing to the cost reduction of highly efficient III-V solar cell technologies.
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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.