Surface and conformational characteristics of As₄₀S₆₀glass films prepared by continuous-wave laser deposition

As40S60 glass films have been prepared by continuous-wave laser deposition from targets of bulk glass. This deposition technique allows the tailoring of the thickness profile of the samples by setting the light intensity distribution and is being explored for the fabrication of free-form infrared optics on the basis of chalcogenide glasses. The present paper reports on the surface and conformational characteristics of As40S60 glass films prepared by this deposition technique. A heterogeneous glass conformation has been observed in the amorphous fabric of the as-deposited samples. Network-glass type conformation seems to be favored by the concurrent laser irradiation of the samples throughout the deposition, while a molecular-glass type conformation occurs when the sample is not concurrently irradiated. Pararealgar molecular units have been found to be present in this case. Laser-induced transformation of β-realgar type molecular units into pararealgar type molecular units seems to take place during the irradiation of the starting material. Etching of the as-deposited samples by 0.1 M NaOH solution seems to lift the occurrence of such molecular units in the amorphous fabric by selective etching of the AsS3/2 network-former molecular units.