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You searched for subject:(Ge2Sb2Te5 Thin Films). Showing records 1 – 2 of 2 total matches.

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1. Washington, Joseph St. Paul. The Local Structure and Kinetics of Ge-Sb-Te Phase Change Materials for use in Solid State Applications.

Degree: PhD, Physics, 2010, North Carolina State University

Recent interest in phase change materials (PCMs) for non-volatile memory applications has been fueled by the promise of scalability beyond the limit of conventional DRAM and NAND flash memory. Typical PCMs such as Ge2Sb2Te5 (GST) require significant nitrogen doping to shift their crystallization temperature (Tx) sufficiently above standard CMOS device operation ranges (~ 80ºC ) but also well below the melting point for thermal stability. Reactive ion etching (RIE) in an Ar/Cl2/CHF3 plasma chemistry is another crucial step en-route to fabricating energy efficient, high density, nano-scaled PCM memory devices, yet it can lead to unfavorable, irreversible modification of the GST material. Chalcogens such as Te in GST can easily diffuse and interact unfavorably with the adjacent materials in the device structure thus negatively impacting the lifetime of a PCM device cell. In light of these implications for the final solid state device, it is necessary to understand and articulate the nature and structural implications of doping/alloying GST, the local structural changes that occur post etch processing, and the nature of the Ge-Sb binary and the Ge-Sb-Te ternary alloys. Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine spectroscopy (XAFS), and in-situ, time resolved, X-ray diffraction (XRD) is used to understand the local structure of nitrogen in GST, and results point to the formation of preferential Ge-N bonding in a chemically ordered germanium nitride local bonding environment in as-deposited and annealed films. XAFS of various GeSb and Ge-Sb-Te glasses in the binary and ternary systems, in conjunction with time resolved XRD, show that Te in thin films of GeSb with gradually increasing Te atomic concentration prevents phase segregation, promotes stability, and induces nucleation. A multi-edge refinement of as-deposited thin films of Ge2Sb2Tex (x=4, 5, 6, 7), shows that Ge-Sb bonds are present in Ge2Sb2Te4 and Ge2Sb2Te5 from EXAFS fits, and these Ge-Sb bonds can also be isolated in the Ge near edge spectra in light of inelastic losses, i.e. shake-up / shake-off effects. The chemical and structural effects of RIE on the crystallization of N-GST is examined via XPS, XAFS, time resolved laser reflectivity and XRD. Time resolved laser reflectivity and XRD show that exposure to various etch and ash chemistries significantly reduces the crystallization speed, while the transition temperature from the rocksalt to the hexagonal phase is increased. XPS and XAFS attribute this to the selective removal and oxidization of N, Ge, Sb, and Te, thus altering the local bonding environment to the detriment of device performance. Advisors/Committee Members: Michael A. Paesler, Committee Chair (advisor), Nicholas C.M. Fuller, Committee Member (advisor), Eric A. Joseph, Committee Member (advisor), John E. Rowe, Committee Member (advisor), David E. Aspnes, Committee Member (advisor), Gerald Lucovsky, Committee Co-Chair (advisor).

Subjects/Keywords: Thin Films; Nitrogen doped Ge2Sb2Te5; Phase Change Materials; EXAFS; Chalcogenides; X-Ray Diffraction

…x29; GST thin films. These techniques reveal the chemical and local bonding environment… …between 0, 13, and 100 sccm for the 100 nm films, but only 100 sccm for the 1000 nm thin film… …transmission IR measurements [32], and is ideal for N-GST thin films on thick bare Si… …Material Modification on the Crystallization Properties of Nitrogen Doped Ge2Sb2Te5… …sample was capped with a thin layer of Nb to prevent surface oxidation, so we increased Rbkg to… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Washington, J. S. P. (2010). The Local Structure and Kinetics of Ge-Sb-Te Phase Change Materials for use in Solid State Applications. (Doctoral Dissertation). North Carolina State University. Retrieved from http://www.lib.ncsu.edu/resolver/1840.16/6241

Chicago Manual of Style (16th Edition):

Washington, Joseph St Paul. “The Local Structure and Kinetics of Ge-Sb-Te Phase Change Materials for use in Solid State Applications.” 2010. Doctoral Dissertation, North Carolina State University. Accessed January 26, 2020. http://www.lib.ncsu.edu/resolver/1840.16/6241.

MLA Handbook (7th Edition):

Washington, Joseph St Paul. “The Local Structure and Kinetics of Ge-Sb-Te Phase Change Materials for use in Solid State Applications.” 2010. Web. 26 Jan 2020.

Vancouver:

Washington JSP. The Local Structure and Kinetics of Ge-Sb-Te Phase Change Materials for use in Solid State Applications. [Internet] [Doctoral dissertation]. North Carolina State University; 2010. [cited 2020 Jan 26]. Available from: http://www.lib.ncsu.edu/resolver/1840.16/6241.

Council of Science Editors:

Washington JSP. The Local Structure and Kinetics of Ge-Sb-Te Phase Change Materials for use in Solid State Applications. [Doctoral Dissertation]. North Carolina State University; 2010. Available from: http://www.lib.ncsu.edu/resolver/1840.16/6241


Indian Institute of Science

2. Vinod, E M. Investigations of Phase Change Memory Properties of Selenium Doped GeTe and Ge2Sb2Te5.

Degree: 2013, Indian Institute of Science

GeTe and Ge2Sb2Te5 alloys are potential candidates for non-volatile phase change random access memories (PCRAM). For electrical data storage applications the materials should have stable amorphous and crystalline phases, fast crystallization time, low power to switch, and high crystallization activation energy (to be stable at normal operating temperatures). Phase change memories can be tuned through compositional variations to achieve sufficient phase change contrast and thermal stability for data retention. Selenium is one of the attractive choices to use as an additive material owing to its flexible amorphous structure and a variety of possible applications in optoelectronics and solar cells. GeSb2Te3Se alloy, in which 25 at.% of Se substituted for Te, show a higher room temperature resistance with respect to parent GeSb2Te4 alloy, but the transition temperature is lowered which will affect the thermal stability. The RESET current observed for Sb65Se35 alloys were reduced and the crystallization speed increased 25 % faster with respect to Ge2Sb2Te5. Alloys of Ga-Sb-Se possess advantages such as higher crystallization temperatures, better data retention, higher switching speed, lower thermal conductivity and lower melting point than the GST, but the resistance ratio is limited to about two orders of magnitude. This affects the resistance contrast and data readability. It is with this background a study has been carried out in GeTe and GeSbTe system with Se doping. Studies on structural, thermal and optical properties of these materials all through the phase transition temperatures would be helpful to explore the feasibility of phase change memory uses. Thin films along with their bulk counterparts such as (GeTe)1-x Sex ( 0 < x ≤ 0.50) and (GST)1-xSex (0 < x ≤ 0.50), including GeTe and GST alloys, have been prepared. The results are presented in four chapters apart from the Introduction and Experimental techniques chapters. The final chapter summarizes the results. Chapter 1 provides an introduction to chalcogenide glasses, phase change memory materials and their applications. The fundamental properties of amorphous solids, basic phase change properties of Ge2Sb2Te5 and GeTe alloys and their applications are presented in detail. Various doping studies on GeTe and Ge2Sb2Te5 reported in literatures are reviewed. The limitations, challenges, future and scope of the present work are presented. In chapter 2, the experimental techniques used for thin film preparation, electrical characterizations, optical characterization and surface characterizations etc. are explained. Chapter 3 deals entirely on Ge2Sb2Te5 films studied throughout the phase transition, by annealing at different temperatures. Changes in sheet resistance, optical transmission, morphology and surface bonding characteristics are analyzed. The crystallization leads to an increase of roughness and the resistance changes to three orders of magnitude at 125 °C. Optical studies show distinct changes in transmittance during phase transitions and the optical… Advisors/Committee Members: Sangunni, K S.

Subjects/Keywords: Amorphous Solids; Phase Change Memory Alloys; Germanium-Tellurium Phase Change Memory Alloys; Germanium-Antimony-TelluriumPhase Change Memory Alloys; Amorphous Semiconductors; Selenium Doped GeTe Alloys; Selenium Doped GeSbTe Alloys; Chalcogenide Glasses; GeTe Thin Films; GST (Germanium-Antimony-Tellurium) Films; Phase Change Random Access Memory; Phase Change Memory Materials; Ge2Sb2Te5 Thin Films; Ge-Te Phase Change Memory Alloys; Ge-Sb-Te Phase Change Memory Alloys; Materials Science

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Vinod, E. M. (2013). Investigations of Phase Change Memory Properties of Selenium Doped GeTe and Ge2Sb2Te5. (Thesis). Indian Institute of Science. Retrieved from http://etd.iisc.ernet.in/2005/3339 ; http://etd.iisc.ernet.in/abstracts/4204/G25733-Abs.pdf

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Vinod, E M. “Investigations of Phase Change Memory Properties of Selenium Doped GeTe and Ge2Sb2Te5.” 2013. Thesis, Indian Institute of Science. Accessed January 26, 2020. http://etd.iisc.ernet.in/2005/3339 ; http://etd.iisc.ernet.in/abstracts/4204/G25733-Abs.pdf.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Vinod, E M. “Investigations of Phase Change Memory Properties of Selenium Doped GeTe and Ge2Sb2Te5.” 2013. Web. 26 Jan 2020.

Vancouver:

Vinod EM. Investigations of Phase Change Memory Properties of Selenium Doped GeTe and Ge2Sb2Te5. [Internet] [Thesis]. Indian Institute of Science; 2013. [cited 2020 Jan 26]. Available from: http://etd.iisc.ernet.in/2005/3339 ; http://etd.iisc.ernet.in/abstracts/4204/G25733-Abs.pdf.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Vinod EM. Investigations of Phase Change Memory Properties of Selenium Doped GeTe and Ge2Sb2Te5. [Thesis]. Indian Institute of Science; 2013. Available from: http://etd.iisc.ernet.in/2005/3339 ; http://etd.iisc.ernet.in/abstracts/4204/G25733-Abs.pdf

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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