Showing papers on "Chemical bath deposition published in 1991"

Chemical Bath Deposition of Cadmium Sulfide Thin Films

Abstract: Chemical bath deposition of cadmium sulfide thin films (up to 0.2 µm) from ammonia/ thiourea/Cd2+solutions on SnO2 and CuInSe2 substrates has been studied in situ by using for the first time capacitance measurements during the formation reaction. The growth is shown to proceed through three consecutive phases: an induction period, a linear growth range and a saturation range. The effect of various parameters on the growth is presented (temperature, concentrations of reacting species, type and activation of the substrate). The growth rate is temperature activated with an activation energy of about 20 kcal/mol which is characteristic of a limiting step associated with a chemical surface reaction. The saturation of the growth rates for higher concentrations of thiourea and cadmium also indicates the presence of consecutive elementary steps, as adsorption steps for instance, in the deposition mechanism. This explains the high quality, of the CdS films obtained by this method (adherence,covering properties, homogeneity). The films are n type with doping levels of a few 1016cm-3, they have a preferential orientation along the c axis in the hexagonal structure and good optical properties.

Metal sulfide thin films on glass as solar control, solar absorber, decorative, and photographic coatings

Abstract: An overview of the optical transmittance and reflectance characteristics of selected metal sulfide thin-film coatings obtained on glass substrates by chemical bath deposition is presented. The focus is on their application as solar control coatings, solar absorber coatings, decorative coatings, and as an imaging medium. Coatings of PbS-CuxS, Bi2S3- CuxS, SnS-CuxS, and ZnS-CuxS offer a range of solar control characteristics. Depending on the thickness of the individual films, solar absorptance of approximately equals 90% has been observed for SnS-CuxS and ZnS-CuxS thin films. Pleasant shades of colors observed in reflected daylight due to the thin film interference in these films together with the ease with which chemically deposited coatings can be obtained on cylindrical or planar substrates suggest the use of these films as decorative coatings. An application of these films as a photographic medium is possible based on the photo-accelerated chemical deposition of PbS and Bi2S3 thin films by which a specularly reflective image is obtained.