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Sb-Te Phase-change Materials under Nanoscale Confinement

Ihalawela, Chandrasiri A.
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1449245846

Abstract Details

2016, Doctor of Philosophy (PhD), Ohio University, Physics and Astronomy (Arts and Sciences).
Size, speed and efficiency are the major challenges of next generation nonvolatile memory (NVM), and phase-change memory (PCM) has captured a great attention due to its promising features. The key for PCM is rapid and reversible switching between amorphous and crystalline phases with optical or electrical excitation. The structural transition is associated with significant contrast in material properties which can be utilized in optical (CD, DVD, BD) and electronic (PCRAM) memory applications. Importantly, both the functionality and the success of PCM technology significantly depend on the core material and its properties. So investigating PC materials is crucial for the development of PCM technology to realized enhanced solutions. In regards to PC materials, Sb-Te binary plays a significant role as a basis to the well-known Ge-Sb-Te system. Unlike the conventional deposition methods (sputtering, evaporation), electrochemical deposition method is used due to its multiple advantages, such as conformality, via filling capability, etc. First, the controllable synthesis of Sb-Te thin films was studied for a wide range of compositions using this novel deposition method. Secondly, the solid electrolytic nature of stoichiometric Sb2Te3 was studied with respect to precious metals. With the understanding of 2D thin film synthesis, Sb-Te 1D nanowires (18 – 220 nm) were synthesized using templated electrodeposition, where nanoporous anodic aluminum oxide (AAO) was used as a template for the growth of nanowires. In order to gain the controllability over the deposition in high aspect ratio structures, growth mechanisms of both the thin films and nanowires were investigated. Systematic understanding gained thorough previous studies helped to formulate the ultimate goal of this dissertation. In this dissertation, the main objective is to understand the size effect of PC materials on their phase transition properties. The reduction of effective memory cell size in conjunction with multilevel cells could be promising to achieve high data densities. However the size reduction may result in changes in material properties. If phase transition properties of the materials are also tunable with respect to the size, then more attractive solutions could be realized. So we have reported the size effect on crystallization temperature of prototypical Sb2Te3 nanowires synthesized in AAO templates. Moreover, we have found that the reduction of nanowire size can elevate the crystallization temperature, which is crucial for data retention in PCM technology. Energy dispersive X-ray spectroscopy, X-ray diffraction, electron microscopy and electrical resistivity measurements were used to characterize the composition, structure, morphology, and phase transition properties of the materials. We believe that this dissertation will provide new insights into the size effect of PC materials in addition to the controllable synthesis of PC thin films and nanowires through the novel electrochemical method.
Gang Chen (Advisor)
David Drabold (Committee Member)
Martin Kordesch (Committee Member)
Hao Chen (Committee Member)
180 p.
Chemistry; Condensed Matter Physics; Materials Science
Antimony Telluride; Electrodeposition of Phase-change Materials; Phase-change Nanowires; Size dependent crystallization of Sb-Te Phase-change Nanowires;

Recommended Citations

Citations

  • Ihalawela, C. A. (2016). Sb-Te Phase-change Materials under Nanoscale Confinement [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1449245846

    APA Style (7th edition)

  • Ihalawela, Chandrasiri. Sb-Te Phase-change Materials under Nanoscale Confinement. 2016. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1449245846.

    MLA Style (8th edition)

  • Ihalawela, Chandrasiri. "Sb-Te Phase-change Materials under Nanoscale Confinement." Doctoral dissertation, Ohio University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1449245846

    Chicago Manual of Style (17th edition)

ohiou1449245846
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This open access ETD is published by Ohio University and OhioLINK.