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NON-CRYSTALLINE OXIDES AND CHALCOGENIDES: A NEW PARADIGM BASED ON AB INITIO QUANTUM CHEMISTRY CALCULATIONS FOR SHORT RANGE ORDER AND PROPERTIES, AND BOND-CONSTRAINT THEORY FOR NETWORK CONNECTIVITY, NETWORK DISRUPTION AND CHE

G. Lucovsky1,*

Affiliation

  1. Department of Physics, NC State University, Campus Box 8202, Raleigh, NC 27695-8202, USA

Abstract

The bonding and properties of non-crystalline chalcogenide glasses and thin films are compared with those of non-crystalline bulk glass and thin film oxides. This approach provides a methodology for understanding some of the more important applications of chalcogenides in the context of significant qualitative similarities and quantitative differences between these two classes of technologically important non-crystalline solids. The theoretical foundation for comparisons is two-fold: i) ab initio quantum chemistry calculations on small clusters to study short range order and properties dependent of this scale of order, and ii) bond constraint theory of identify the effects of network connectivity and bonding constraints. This approach is first applied to infrared effect charges and differences in the photo-structural network response between As2S3 and GeS2. The methodology is then extended to comparisons between thin film silicate alloys, and their chalcogenide counter-parts, with emphasis on understanding the broader range of reversible memory and transport behaviors in the chalcognide films and glasses. Finally, self organization is addressed in oxide and chalcogenide thin films, providing the basis for device applications. These include ternary silicate alloys with irreversible self-organizations that are enabling for gate dielectrics, as well reversible self organizations in GeTe-Sb2Se3 alloys for information storage in read/write optical memories..

Keywords

Continuous random networks, Chalcogenide alloys, SiO2 alloys, Silicates, Ab initio calculations, Bond constraint theory, Floppy and stressed-rigid films, Intermediate phases, Network disruption and modification, Chemical phase separation.

Submitted at: May 19, 2005
Accepted at: July 21, 2005

Citation

G. Lucovsky, NON-CRYSTALLINE OXIDES AND CHALCOGENIDES: A NEW PARADIGM BASED ON AB INITIO QUANTUM CHEMISTRY CALCULATIONS FOR SHORT RANGE ORDER AND PROPERTIES, AND BOND-CONSTRAINT THEORY FOR NETWORK CONNECTIVITY, NETWORK DISRUPTION AND CHE, Journal of Optoelectronics and Advanced Materials Vol. 7, Iss. 4, pp. 1691-1706 (2005)