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Electron beam crystallization of amorphous silicon thin films in the solid phase regime and assisted simulations by finite element method

: Saager, Stefan


European Commission:
32nd European Photovoltaic Solar Energy Conference and Exhibition, EU PVSEC 2016 : 20 - 24 June 2016, Munich, Germany
Munich, 2016
ISBN: 3-936338-41-8
European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC) <32, 2016, Munich>
Conference Paper
Fraunhofer FEP ()
electron beam crystallization; silicon thin films; explosive solid phase crystallization; crucible-freecrucible-free electron beam evaporation

The impact of an electron beam (EB) treatment on a-Si coated Si-substrates was investigated by SEM and EBSD analysis. EB processing of a-Si layers by line scanning led to the formation of a narrow grained polycrystalline structure, which is characteristically for an explosive solid phase crystallization. By increasing the EB energy density an undesired delamination of the Si thin film was observed. However, an epitaxial layer regrowth with the similar crystallographic orientation of the (001) Si substrate could be reached by applying a lower EB energy density and by a sequential raise to a tenth of the EB power in comparison to line scanning experiments. By finite element simulations, the reason for layer delamination could be revealed by calculating the temperature and stress field during the EB treatment of the thin film-substrate-system: Due to thermal expansion during the EB line scans the elastic strain energy density accumulates and reaches a critical level. If the value exceeds the a-Si/c-Si interface energy, layer delamination during the EB process is caused.