Thin GaAsxSy films are deposited on Mo substrates by reactive radio-fr
equency sputtering of a polycrystalline GaAs target by adding H2S to t
he discharge gas (Ar). We used optical emission spectroscopy and mass
spectrometry to study the As-S exchange reaction activity during sputt
er deposition as a function of different sputtering parameters. The an
alysis of electrical and photoelectrical properties of the Schottky ju
nctions realised, Mo/GaAsS/Au, shows that with an increase in sulfur c
oncentration there is: an improvement of the gold/semiconductor interf
ace (decreasing interface index and increasing barrier height); a sign
ificant lowering of grain boundary electrical activities. We have thus
prepared a ternary polycrystalline compound GaAsxSy which presents pr
omising electrical and photoelectrical properties, even for films as t
hin as a few microns with grains of about one micron.