Hydrogenation of Dislocation-Limited Heteroepitaxial Silicon Solar Cells: Preprint.
Author: Bolen, M. L.; Grover, S.; Teplin, C. W.; Bobela, D.; Branz, H. M.; Stradins, P.
Pages/Volumes: 7 pp.
Publication Year: 2012
Notes: Presented at the 2012 IEEE Photovoltaic Specialists Conference, 3-8 June 2012, Austin, Texas
Document Type: Conference Paper
NTIS/GPO Number: 1045048
Subject Code Description: Solar Energy - Photovoltaics
Abstract: Post-deposition hydrogenation by remote plasma significantly improves performance of heteroepitaxial silicon solar cells. Heteroepitaxial deposition of thin crystal silicon on sapphire for photovoltaics (PV) is an excellent model system for the study and improvement of deposition on inexpensive Al2O3-coated (100) biaxially-textured metal foils. Without hydrogenation, PV conversion efficiencies are less than 1% on our model system. Performance is limited by carrier recombination at electrically active dislocations that result from lattice mismatch, and other defects. We find that low-temperature hydrogenation at 350 degrees C is more effective than hydrogenation at 610 degrees C. In this work, we use measurements such as spectral quantum efficiency, secondary ion mass spectrometry (SIMS), and vibrational Si-H spectroscopies to understand the effects of hydrogenation on the materials and devices. Quantum efficiency increases most at red and green wavelengths, indicating hydrogenation is affecting the bulk more than the surface of the cells. SIMS shows there are 100X more hydrogen atoms in our cells than dangling bonds along dislocations. Yet, Raman spectroscopy indicates that only low temperature hydrogenation creates Si-H bonds; trapped hydrogen does not stably passivate dangling-bond recombination sites at high temperatures.
Accession Number: 54101
Library Notes: NPL-1206 REV
Report Numbers: CP-5200-54101
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