The tailoring of the composition of Ag-As-Se amorphous films using optically-induced solid state reaction between Ag and As30Se70 films

A new technique of step-by-step optic ally-induced solid state reaction of Ag with As30Se70 amorphous films, which has allowed the design of films wit h exact silver concentration, is reported. The composition of the As-Se fil ms was chosen to be As30Se70 which is the most favorable for optically-indu ced solid state reaction, because it yields homogeneous photodoped products . The host As,,Se,, films were photodoped by consecutive dissolving thin (s imilar to 20 nm) layers of silver and resulted in homogeneous films of good optical quality. The silver concentration of homogeneous samples ranged be tween 1 and 21 at.%. We have analyzed in detail the influence of the silver doping in the host material on optical and thermal properties, and its str ucture. The photodoped films produced a single-phase homogeneous material u p to 21 at.% of Ag. There is evidence of Se-Se bonds breaking in photo-dope d materials with increasing silver doping. Results of all three analytical techniques have helped to understand the processes taking place during silv er photodissolution. (C) 2001 Elsevier Science Ltd. All rights reserved.