Kinetics of photo-darkening and self-bleaching in amorphous As2S3 and As2Se3 thin films

• Published in: Physica status solidi. PSS-RRL. Rapid research letters 2007-03, Vol.1 (2), p.R74-R76
• Main Authors: Munzar, M., Tichý, L.
• Format: Article
• Language: English
• Subjects: 42.70Gi; 61.80.Ba; 71.55.Jv; Amorphous semiconductors; glasses; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics
• ISSN: 1862-6254; 1862-6270
• DOI: 10.1002/pssr.200600082

The kinetics of photo‐darkening of amorphous As2S3 and a‐As2Se3 thin films follows a single exponential, but the magnitude and the rate of the process is higher in case of As2S3. The kinetics of self‐bleaching (dark relaxation) in advance photo‐darkened state follows a stretched exponential (SRE) with different stretching parameter for a‐As2S3 and a‐As2Se3. Within the J. C. Phillips approach we suppose that photo‐darkening in amorphous As2S3 films is, to some extent, accompanied by changes in short‐range order interactions, while photo‐darkening of amorphous As2Se3 is accompanied rather by changes in Coulomb interactions. The self‐bleaching process reduced the magnitude of photo‐darkening up to 45% and 60% for amorphous As2S3 and As2Se3 films, respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) Amorphous chalcogenides are prospective materials for optical memories and data storage. Relevant photo‐induced phenomena are accompanied by various time dependent processes. Kinetics of self‐bleaching in amorphous As2S3and a‐As2Se3 thin films (photo‐darkened in advance) follow stretched exponentials with comparable rate constants but different stretching parameters. Self‐bleaching is a rather slow process and reached the nearly saturated state only after approximately two months.