Document Type

Conference Proceeding

Language

eng

Publication Date

3-13-2015

Publisher

Society of Photo-Optical Instrumentation Engineers (SPIE)

Source Publication

Proceedungs of SPIE 9364, Oxide-based Materials and Devices VI

Source ISSN

9781628414547

Abstract

Germanium telluride (GeTe) is a phase change material (PCM) that undergoes an exponential decrease in resistance from room temperature to its transition temperature at approximately 200 °C. Its resistivity decreases by as much as six orders of magnitude between amorphous and crystalline phases as it is heated. Chalcogenides such as GeTe have been utilized typically in nonvolatile optical memories such as CDs, DVDs, and Blu-ray discs, where the change in reflectivity between phases gives enough contrast for ON and OFF bits. Research over the past several years has begun to characterize the electronic control of PCM thin films for advanced electronic memory applications. By applying a voltage to control its resistance and crystallinity, GeTe has become a candidate for ultra-fast switching electronic memory, perhaps as an alternative to Flash memory. In this research, micro-scale PCM cells were fabricated using RF sputtering of a GeTe target and electron-beam evaporation on c-Si, SiO2/Si, Si3N4/Si, and Al2O3. Characterizations of the crystallization process were completed with spectroscopic ellipsometry (SE), varied voltage, and varied temperature in order to draw a comparison of the switching mechanism between thermally and electronically induced transition. The results show an optical contrast of ∆n + i∆k = -0.858 + i1.056. Heat conduction experiments prove a growth dominated crystallization and fracturing of conductive crystallites when deposited on Al2O3. PCM cells exhibit memory-like I-V curves for smaller cell dimensions according to the trap-limited conduction model in chalcogenides. RF structures show the capability of being utilized as improved RF switches.

Comments

Published version. Published as a part of Proceedings of SPIE 9364, Oxide-based Materials and Devices VI, (13 March 2015): 93640G. DOI. © 2015 Society of Photo-Optical Instrumentation Engineers (SPIE). Used with permission.

Ronald A. Coutu was affiliated with Air Force Institute of Technology at the time of publication.

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