Defects in TiO 2 films on p +-Si studied by positron annihilation spectroscopy

Paul G Coleman, Charlene J Edwardson, A Zhang, X Ma, X Pi, D Yang

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Variable-energy positron annihilation spectroscopy has been applied to the study of defects in TiO 2/p +-Si structures, in the as-grown state and after annealing in vacuum and in hydrogen, to investigate whether annealing (and film thickness) resulted in an increase of vacancy-type defects in the oxide films. It was found that the concentration of such defects remained unchanged after vacuum annealing for all films studied, but after H 2 annealing more than doubled for 150 nm-thick films, and increased by an order of magnitude for 100 nm-thick films. The nature of the vacancies was examined further by measuring high-precision annihilation lines and comparing them with a reference Si spectrum. The changes observed in the ratio spectra associated with oxygen electrons suggest that the defects are oxygen vacancies, which have been shown to enhance electroluminescence from TiO 2/p +-Si heterostructure-based devices.
Original languageEnglish
Pages (from-to)625-628
Number of pages4
JournalMaterials Science and Engineering : B
Issue number8
Publication statusPublished - 15 May 2012


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