Gallium–lanthanum–sulphide amorphous thin films prepared by pulsed laser deposition

Thin amorphous gallium–lanthanum–sulphide films were prepared by pulsed laser deposition method. The prepared layers were characterized in terms of the structure (using Raman scattering spectroscopy), chemical composition (by energy-dispersive X-ray analysis), and optical properties (employing variable angle spectroscopic ellipsometry). Following Raman spectroscopy results, it is supposed that the structure of the bulk glass and corresponding thin films is formed by GaS4 tetrahedra and LaS8 structural units. The study of photo- and thermally induced phenomena in prepared amorphous chalcogenides shows photoinduced decrease of refractive index (∼1–2%) under cw (473 nm) or pulsed (248 nm) laser irradiation and annealing-induced decrease of refractive index (∼2%), respectively.