Aging process of photosensitive chalcogenide films deposited by electron beam deposition

• Published in: Journal of alloys and compounds 2011-07, Vol.509 (27), p.7330-7336
• Main Authors: Charpentier, F., Dussauze, M., Cathelinaud, M., Delaizir, G., Kamitsos, E.I., Adam, J.-L., Bureau, B., Nazabal, V.
• Format: Article
• Language: English
• Subjects: Aging; Aging (artificial); Aging (natural); Amorphous semiconductors; glasses; Arsenic; Bandpass filters; Chalcogenide; Chalcogenides; Chemical Sciences; Coating; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Deposition; Electron beams; Evaporation; Exact sciences and technology; Material chemistry; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Optical waveguide; Photosensitivity; Physics; Raman spectroscopy; Thin film
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2011.04.054

► Ge 15Sb 20S 65 and As 30Se 50Te 20 chalcogenide amorphous films were deposited by EBD. ► The structure of both bulk and thin film has been studied by far-IR and Raman spectroscopy. ► Both films were found to be photosensitive as manifested by the shift of their optical band-gap. ► Aging was found to induce also morphological changes, as growth of arsenic trioxide micro-crystals. Chalcogenide films attract broad interest due to their use as optical components like narrow band-pass filters, omnidirectional reflectors cladding, all-optical signal processing devices or optochemical sensors. Ge 15Sb 20S 65 and As 30Se 50Te 20 chalcogenide amorphous films were deposited by electron beam deposition (EBD) using their corresponding bulk glasses as targets. The structure of both bulk and thin film has been studied by far-IR and Raman spectroscopy. This study investigated an ordinary aging behavior of the chalcogenide films by exposing them to natural light under atmospheric conditions for a period of six months. Both films were found to be photosensitive as manifested by the shift of their optical band-gap to shorter or longer wavelength depending on chemical composition. Aging was found to induce also morphological changes, most notably the likely growth of arsenic trioxide micro-crystals on the surface of As 30Se 50Te 20 films. Such effects were discussed in terms of photo-oxidation and photo-hydrolysis phenomena, the extent of which was found to be relatively limited for Ge 25Sb 10S 65 films. The larger stability of the latter films against crystal growth at the surface was associated with the ability of germanium to bond to diffusing oxygen atoms in germanium-oxysulfide tetrahedral arrangements.