Post-Annealing Effects on Cu3BiS3 Thin Films Grown by Chemical Bath Deposition Technique

Cu3BiS3 thin films were grown by a chemical bath deposition technique for use in inexpensive photovoltaic devices. The post-annealing effects on the morphological, structural, stoichiometric, optical, and electrical properties were investigated by using FE-SEM, XRD, EDS, UV-Vis spectrophotometry, and Hall measurements. The as-grown Cu3BiS3 thin films showed flower-like crystals with a fully covered surface and a high absorption coefficient of similar to 10(5)cm(-1) with a 1.42 eV optical bandgap energy. The carrier concentration, resistivity, and mobility were similar to 10(16) cm(-3), 3.38 x 10(-1)Omega . cm, and 7.12 x 10(1) cm(2).V-1 s(-1), respectively. As the annealing time increased, the flower-like crystals on the surface of the sample became larger, showing the influence of post-annealing on the crystallinity of the Cu3BiS3 thin film. An XRD spectrum of the sample annealed at 300 degrees C for 30 min showed several reflection peaks around 29 degrees. The absorption coefficient of the post-annealed sample slightly decreased and the bandgap energy increased. The carrier concentration increased, while the resistivity and mobility of the annealed films decreased. Moreover, homogeneity and chemical composition ratios were estimated from the energy dispersive spectrometer data.