S. Kitova et al., INFRARED PHOTOGRAPHY BASED ON VAPOR-DEPOSITED SILVER SULFIDE THIN-FILMS, Journal of imaging science and technology, 38(5), 1994, pp. 484-488
Ag2S as a narrow band-gap semiconductor is appropriate for photoimagin
g in the infrared (IR) region. Coevaporation of silver and sulfur from
separate sources is used for preparing Ag2S thin films with different
Ag/S ratios. The structure of the films is examined by transmission e
lectron microscopy, electron diffraction, and x-ray diffraction. We fi
nd that upon illumination latent-image centers or print-out silver spe
cks are formed predominantly in the bulk of the Ag2S grains. Their gro
wth in a stabilized physical developer becomes possible after appropri
ate etching of the exposed Ag2S films. The photographic parameters of
the films are related to the processing conditions, film thickness, an
d Ag/S ratio. It is shown that after proper processing, Ag2S thin film
s with stoichiometric composition or excess amount of silver can be su
ccessfully used as either negative or positive high-resolution photogr
aphic materials in the IR region. A maximum resolution of 1600 lines/m
m has been achieved so far.