Raman spectroscopy of chalcogenide thin films prepared by PLD

Chalcogenide glasses have many technological applications as a result of their particular optical and electrical properties. Ge-Se and Ag-Ge-Se systems were recently studied and tested as new materials for building non-volatile memories. Following these ideas, thin films of Ge-Se and Ag-Ge-Se were deposited using pulsed laser deposition (PLD). Ag was sputtered over binary films (for a composition between 0.05 and 0.25 Ag atomic fraction) and photo-diffused afterwards. Thus, three kinds of samples were analyzed by means of Raman spectroscopy, in order to provide information on the short- and medium-range order: PLD binary films before Ag doping, after Ag doping and PLD ternary films. Before Ag doping, binary films exhibited Ge-Se corner-sharing tetrahedra modes at 190 cm-1, low scattering from edge-sharing tetrahedra at 210 cm-1, and Se chains at 260 cm-1 (stretching mode). However, after the diffusion process was complete, we observed an intensity reduction of bands centered at 210 cm-1 and 260 cm-1. The spectra of the photo-diffused films were similar to those of films deposited using a ternary target. Relaxation effects in binary glasses were also analyzed. Results were compared with those of other authors.