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Pyrite phase FeS2 thin films have been grown by a two-stage process of chemical bath deposition followed by sulfurization. Thiourea and thioacetamide were used as sulfur precursors in separate baths.  The deposition time was controlled for 1, 2, and 3 hours respectively. The as-deposited films were sulfurized at temperatures of 250 oC and 500 oC to form the pyrite phase. The effect of deposition time and sulfurization temperature on the structure, morphology and optical properties of the iron pyrite films obtained from the two separate baths were studied and compared. X-ray diffraction analyses established the formation of the pyrite phase in all the films after sulfurization, in addition to iron (II) oxide hydrate as impurities. All films showed further improvement in pyrite formation, crystallinity as well as an increase in crystallite size after sulfurizing at 500 oC. EDAX and SEM microscopy showed that the iron pyrite films produced from the bath containing thiourea, had better crystallinity and a higher iron content. The optical band gap of the iron pyrite films obtained with thiourea, was 2.1, 1.9 and 1.6 eV for the various deposition times. With thioacetamide, the band gap was 1.4 eV, for the deposition time of 3 hours.

The tuneable band gap property of Cadmium-sulphur-selenide (CdS 1-x Se x ) thin film makes it an appropriate material for a wide range of optoelectronic applications and this has aroused a lot of interest. In this paper, we report the study of Cadmium-sulphur-selenide (CdS 1-x Se x ) thin films, successfully grown on commercial glass slide substrate by the chemical bath deposition technique. The effect of selenium content (x value) on the structural, and some optical properties have been studied. The bath solution contained cadmium acetate dehydrate [Cd(CH 3 COO) 2 ·2H 2 O], sodium selenosulphate [Na 2 SeSO 3 ] and thiourea [CS(NH 2 ) 2 ] were used as the sources of Cd 2+ , Se 2− and S 2+ , respectively. Tartaric acid (C 4 H 6 O 6 ) was used as a complexing agent. The pH of the solution was adjusted to 12 by drop-wise addition of ammonia. The bath temperature was kept at 90˚C for a deposition time of 1 hour. Post deposition annealing processes of the thin films were performed in a furnace at a temperature of 400˚C for two hours. Both as-deposited and annealed films were characterised by Powder X-Ray Diffraction, Scanning Electron Microscopy, UV-Visible Optical Absorption Spectroscopy and Energy Dispersive X-Ray Analysis. Optical absorption data analysis indicates that direct allowed transitions occur in the films. The band gap of the as-deposited CdS 1-x Se x decreased linearly from 2.34 eV to 1.48 eV, with increasing selenium content, and in the annealed samples, decreased from 1.84 eV to 1.36 eV. X-ray diffraction measurements revealed, that pure CdS, and CdSe had mixed hexagonal and cubic phases. All the remaining ternary compounds were composed of cubic CdS and hexagonal CdSe phases. The annealed samples showed well defined and more intense peaks, suggesting an improvement in crystallinity. The average grain size increased slightly with increasing selenium content. SEM micrographs showed that the films were compact with a smooth texture and good coverage across the entire area of the substrate.

CTS thin films have been prepared by soft annealing and sulfurization of electrodeposited Cu-Sn precursors. The stacked elemental layer approach was used to deposit the elemental precursors on an ITO substrate using a two-electrode electrochemical cell, with graphite plate as the counter electrode. The stacked metallic layer was then soft annealed in an Argon atmosphere at 350 °C and subsequently, sulfurized at different temperatures of 500 0C and 550 0C for one hour to form CTS films. The films have been characterized by a variety of techniques. From the XRD analysis, the CTS thin films obtained at a sulfurization temperature of 500 oC showed the coexistence of SnS, Cubic-Cu2Sn3S7 and hexagonal-Cu4S16Sn7 phases. The majority phase was clearly identified as cubic-Cu2SnS3, with (111) preferential orientation. For the films sulfurized at 550 oC, the pattern of prominent peaks showed the presence of the Hexagonal-Cu4S16Sn7 phase of CTS with preferred orientation along the (202) plane. There were relatively fewer low intensity peaks assigned to the secondary phases, indicating an improvement in CTS purity at the higher sulfurization temperature. SEM images of the CTS films show a compact, homogenous morphology, with densely packed grains. The films sulfurized at 550 oC, showed better homogeneity. EDAX spectra of the sulfurized alloy precursors were consistent with the formation of CTS. The film obtained at the lower sulfurization temperature had two band gaps as a consequence of the mixture of phases present in the sample. The film obtained at the higher sulfurization temperature had an energy band gap of 1.5 eV, which falls within the range of values reported in literature. The present work provides a new synthesis route for the electrodeposition of CTS thin film for device applications.

Single phase lead tin sulfide (PbSnS) thin films have been successfully deposited on ITOcoated glass substrates using a 3-electrode electrochemical cell having graphite as the counter electrode and Ag/AgCl as the reference electrode. In this single-step electrodeposition, the PbSnS precursor thin film was directly electrodeposited on the conductive substrate from the electrolytic bath solution which contained Pb(NO 3 ) 2 , SnCl 2 .2H 2 O and Na 2 S 2 O 3 . This was followed by annealing in air at 250 °C for an hour to improve the crystallinity. The annealed films were characterized by a variety of techniques. Powder X-ray diffraction revealed peaks which were indexed to the orthorhombic phase of PbSnS with preferred orientation along the (112) plane. Seebeck coefficient studies confirmed the type of charge carrier of the film. SEM micrographs showed a compact morphology composed of spherically shaped well defined grains covering the entire substrate. EDAX analysis of the film was consistent with the formation of PbSnS. Optical absorption measurements revealed the existence of a direct transition with an estimated band gap of 1.68 eV