Print Email Facebook Twitter Migration of Open Volume Deficiencies in Hydrogenated Amorphous Silicon during Annealing Title Migration of Open Volume Deficiencies in Hydrogenated Amorphous Silicon during Annealing Author Melskens, J. (TU Delft Photovoltaic Materials and Devices; Eindhoven University of Technology) Eijt, S.W.H. (TU Delft RST/Fundamental Aspects of Materials and Energy) Schouten, M. (TU Delft Photovoltaic Materials and Devices) Vullers, A.S. (TU Delft Photovoltaic Materials and Devices; TU Delft RST/Fundamental Aspects of Materials and Energy) Mannheim, Awital (External organisation) Schut, H. (TU Delft RST/Neutron and Positron Methods in Materials) Macco, Bart (Eindhoven University of Technology) Zeman, M. (TU Delft Photovoltaic Materials and Devices; TU Delft Electrical Sustainable Energy) Smets, A.H.M. (TU Delft Photovoltaic Materials and Devices) Department Electrical Sustainable Energy Date 2017 Abstract The nanostructure of hydrogenated amorphous silicon (a-Si:H) is studied by means of doppler broadening positron annihilation spectroscopy (DB-PAS) and Fourier transform infrared (FTIR) spectroscopy. The evolution of open volume deficiencies is monitored during annealing, demonstrating that small vacancies and other small vacancy clusters that are initially present in the a-Si:H nanostructure agglomerate into larger vacancy clusters. The migration of open volume deficiencies is less pronounced for a-Si:H deposited at higher hydrogen-to-silane gas flow rate ratio, R. FTIR spectroscopy reveals the presence of a peculiar peak in the refractive index in the infrared - and hence the calculated mass density - which occurs just before H effusion from the films starts. The combined results of DB-PAS and FTIR spectroscopy indicate that a stress buildup caused by the accumulation of H2 in agglomerating vacancies during annealing can explain the sudden mass density increase. At higher temperatures, stress is released with the onset of H effusion. The H effusion consists of a two-stage process involving small open volume deficiencies and nanosized voids, contrasting earlier interpretations. The reduced amount of hydrogen migration and enhanced hydrogen passivation degree are suggested as key factors to the reduced light-induced degradation associated with increased R values. Subject Annealingdefectshydrogenated amorphous silicon (a-Si:H)nanostructurevacancies To reference this document use: http://resolver.tudelft.nl/uuid:a7603bb2-0be8-4b32-af92-a3c7f85f253f DOI https://doi.org/10.1109/JPHOTOV.2016.2646421 ISSN 2156-3381 Source IEEE Journal of Photovoltaics, 7 (2), 421-429 Bibliographical note Accepted Author Manuscript Part of collection Institutional Repository Document type journal article Rights © 2017 J. Melskens, S.W.H. Eijt, M. Schouten, A.S. Vullers, Awital Mannheim, H. Schut, Bart Macco, M. Zeman, A.H.M. Smets Files PDF 12043783.pdf 846.07 KB Close viewer /islandora/object/uuid:a7603bb2-0be8-4b32-af92-a3c7f85f253f/datastream/OBJ/view