  Chalcogenide glass-silver heterostructures are candidates for photoresist and
diffractive optical applications. To optimize their processing, we report the
kinetics of Ag photo-dissolution in As2S3 matrix using in-situ optical
transmission/reflection measurements and real time atomic force microscopy
(AFM) imaging under optical illumination. The results indicate that
photodissolution occurs in three stages with the extent and kinetics of each
stage depending strongly on Ag film thickness. By contrast, the
photo-dissolution is found to be independent of As2S3 matrix thickness. The
extent of three stages also depends strongly on the laser dose and can be
reduced to two stages at higher laser fluence. A comparative study of two
oppositely stacked sample configurations: As2S3/Ag/glass and Ag/As2S3/glass
show that the heterostructures respond differently to light illumination. For
the former, Ag dissolves completely into As2S3 matrix at a faster rate than for
the latter case. The origin of this difference is established by energy
dispersive X-ray spectroscopy and AFM measurements.
