| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1665175 | Thin Solid Films | 2014 | 5 Pages |
•Report Raman and PL spectra•Determine two band gaps using photo-reflectivity analysis•Analyse their temperature dependence and find average phonon temperature•Clarify the nature of defects from temperature and excitation power analysis of PL spectra•Propose a model of radiative recombination
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.
