Er3+-doped Ga-Ge-Sb-S glass thin films by PVD deposition

In the frame of the major issues related to global warming and pollution, the microsensor based on mid-infrared (MIR) spectroscopy is a useful tool to allow continuous measurement of different bio-chemicals species that disturb our environment. In the aim of developing a MIR source potentially integrated in a microsensor, we fabricated rare earth doped chalcogenide thin films by different phase vapor deposition (PVD) technics. The RF magnetron sputtering, pulsed laser deposition (PLD) and electron beam evaporation were investigated. The selected glass system is Ge-Ga-(Sb)-S with Er3+ ions doping. Er3+ ions show emissions in NIR and MIR at 1.55 µm (4I13/2→4I15/2)and at 2.8 µm (4I11/2→4I13/2) under excitation at 808 nm. Deposition parameters were optimized for the three PVD techniques based on a comparison to define the higher fluorescence efficiency. Sulphide thin films were characterized by means of transmission, AFM, XPS, SEM, EDS, ellipsometry and Raman spectroscopy to better control the deposition behavior.