Optimisation of low-temperature silicon epitaxy on seeded glass substrates by ion-assisted deposition

• Published in: Journal of crystal growth 2005-07, Vol.280 (3), p.385-400
• Main Authors: Straub, Axel, Inns, Daniel, Terry, Mason L., Huang, Yidan, Widenborg, Per I., Aberle, Armin G.
• Format: Article
• Language: English
• Subjects: A1. Crystal structure; A1. Impurities; A3. Molecular beam epitaxy; A3. Physical vapour deposition processes; Applied sciences; B2. Semiconducting silicon; B3. Solar cells; Cross-disciplinary physics: materials science; rheology; Energy; Exact sciences and technology; Materials science; Methods of crystal growth; physics of crystal growth; Natural energy; Photovoltaic conversion; Physics; Solar cells. Photoelectrochemical cells; Solar energy
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2005.04.011

Using single crystalline Si wafer substrates, ion-assisted deposition (IAD) has recently been shown [J. Crystal Growth 268 (2004) 41] to be capable of high-quality high-rate epitaxial Si growth in a non-ultra-high vacuum (non-UHV) environment at low temperatures of about 600 °C. In the present work the non-UHV IAD method is applied to planar borosilicate glass substrates featuring a polycrystalline silicon seed layer and carefully optimised. Using thin-film solar cells as test vehicle, the best trade-off between various contamination-related processes (seed layer surface as well as bulk contamination) is determined. In the optimised IAD process, the temperature of the glass substrate remains below 600 °C. The as-grown Si material is found to respond well to post-growth treatments (rapid thermal annealing, hydrogenation), enabling respectable open-circuit voltages of up to 420 mV under 1-Sun illumination. This proves that the non-UHV IAD method is capable of achieving device-grade polycrystalline silicon material on seeded borosilicate glass substrates.