Electronic and structural characterisation of Cu3BiS3 thin films for the absorber layer of sustainable photovoltaics

Yakushev, M.V. and Maiello, P. and Raadik, T. and Shaw, M.J. and Edwards, P.R. and Krustok, J. and Mudryi, A.V. and Forbes, I. and Martin, R.W. (2014) Electronic and structural characterisation of Cu3BiS3 thin films for the absorber layer of sustainable photovoltaics. Thin Solid Films, 562. pp. 195-199. ISSN 0040-6090

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    Abstract

    Abstract Thin films of p-type Cu3BiS3 with an orthorhombic wittichenite structure, a semiconductor with high potential for thin film solar cell absorber layers, were synthesised by thermal annealing of Cu and Bi precursors, magnetron sputtered on Mo/glass substrate, with a layer of thermo-evaporated S. The elemental composition, structural and electronic properties are studied. The Raman spectrum shows four modes with the dominant peak at 292 cm-1. Photoreflectance spectra demonstrate two band gaps EgX and EgY, associated with the X and Y valence sub-bands, and their evolution with temperature. Fitting the temperature dependencies of the band-gaps gives values of 1.24 and 1.53 eV for EgX and EgY at 0 K as well as the average phonon energy. Photoluminescence spectra at 5 K reveal two bright and broad emission bands at 0.84 and 0.99 eV, which quench with an activation energy of 40 meV. The photocurrent excitation measurements demonstrate a photoresponse and suggest a direct allowed nature of the band gap.