METAL SULFIDE THIN-FILM PHOTOGRAPHY USING PHOTOACCELERATED CHEMICAL-DEPOSITION OF BISMUTH SULFIDE THIN-FILMS

Metal sulfide thin film (MSTF) photography is based on the photoaccele rated chemical deposition (PACD) of metal sulfide thin films. In this technique, a variation in the intensity of light produced by an object on a growing thin film surface yields a variation in the thickness of the film (0.05-0.5 muM). Due to thin film optical interference, this distribution of thin film thickness is rendered as an image with tone variations of silver, gold, purple, blue, etc., when viewed in dayligh t. We present here the MSTF photography based on bismuth sulfide thin films, obtained on glass substrates of 30 x 20 cm in size. A chemicall y deposited zinc sulfide film (almost-equal-to 0.05 mum) is applied to the glass substrate, without which the bismuth sulfide films peeled f rom the glass substrate. XPS results on the glass-zinc sulfide-bismuth sulfide interfaces revealed diffusion/chemisorption of zinc into the glass substrate and bismuth sulfide thin film. The PACD process is ill ustrated with optical transmittance and reflectance spectra of films d eposited under different intensities (100 to 0.01% of 850 Wm-2) of sol ar radiation. MSTF photographic images obtained at the end of differen t durations of deposition have indicated best image quality for a depo sition time of 45 min under such solar radiation.