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Title:
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Surface passivation for ultrathin Al2O3 layers grown at low temperature by thermal atomic layer deposition
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Author(s):
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Frascaroli, J.; Seguini, G.; Cianci, E.; Saynova - Oosterling, D.S.; Roosmalen, J.A.M. van; Perego, M.
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Published by:
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Publication date:
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ECN
Solar Energy
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28-11-2012
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ECN report number:
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Document type:
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ECN-W--12-057
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Article (scientific)
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Number of pages:
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6
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Published in: Physica Status Solidi (A) (Wiley-VCH Verlag GmbH & Co), , 2013, Vol.210, p.732-736.
Abstract:
Thin layers of Al2O3 with thickness tox8 nm were grown by thermal atomic layer deposition at low temperature of 100 8C and applied to achieve functional surface passivation of crystalline silicon substrates. Measurements of the effective lifetime were performed to characterize the surface passivation effect. Lifetime values in the range of 0.5ms were obtained for Al2O3 films with tox6 nm upon post-deposition annealing (PDA) at 250 8C in N2 atmosphere. However, when the
thickness of the Al2O3 films was reduced to 4 nm, lifetime values well below 0.1ms were observed even after PDA. Combined capacitance–voltage and conductance–voltage measurements were carried out to extract the amount of charges located near the silicon-oxide interface and the density of
electrically active interface states, respectively. The results of the electrical characterization were used to elucidate the intimate physical mechanisms that govern charge recombination at the Al2O3/Si interface.
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