Structural analysis of amorphous Ge0.5Te0.5 by neutron diffraction

Pickart, S. J.; Sharma, Yashna; Neufville, J.P. de

doi:10.1016/0022-3093(79)90034-6

Cited by 32 publications

(8 citation statements)

References 11 publications

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“…It was shown that in the amorphous state there is a random covalent network with Ge four fold coordinated and Te two fold coordinated, 48,49 while others suggest that Ge and Te are both threefold coordinated. 50,51 Some other authors do not agree with this theory and consider that the structure is a mix of 4(Ge):2(Te) and 3(Ge):3(Te) coordinated structural units. 52 For a precise determination of the crystallization temperatures in single films, we performed resistance versus temperature (R-T) measurements.…”

Section: A Getementioning

confidence: 99%

In-situ crystallization of GeTe\GaSb phase change memory stacked films

Velea

Borca

Socol

et al. 2014

Journal of Applied Physics

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Single and double layer phase change memory structures based on GeTe and GaSb thin films were deposited by pulsed laser deposition (PLD). Their crystallization behavior was studied using in-situ synchrotron techniques. Electrical resistance vs. temperature investigations, using the four points probe method, showed transition temperatures of 138 C and 198 C for GeTe and GaSb single films, respectively. It was found that after GeTe crystallization in the stacked films, Ga atoms from the GaSb layer diffused in the vacancies of the GeTe crystalline structure. Therefore, the crystallization temperature of the Sb-rich GaSb layer is decreased by more than 30 C. Furthermore, at 210 C, the antimony excess from GaSb films crystallizes as a secondary phase. At higher annealing temperatures, the crystalline Sb phase increased on the expense of GaSb crystalline phase which was reduced. Extended X-ray absorption fine structure (EXAFS) measurements at the Ga and Ge K-edges revealed changes in their local atomic environments as a function of the annealing temperature. Simulations unveil a tetrahedral configuration in the amorphous state and octahedral configuration in the crystalline state for Ge atoms, while Ga is four-fold coordinated in both as-deposited and annealed samples. V

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Section: A Getementioning

confidence: 99%

In-situ crystallization of GeTe\GaSb phase change memory stacked films

Velea

Borca

Socol

et al. 2014

Journal of Applied Physics

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“…[14] proposed that a randomly bonded 4(Ge):2(Te) coordination described better the experimental inverse photoemission data. Contrary to the aforementioned works, neutron [15] and Mössbauer spectroscopy [16] studies on a-GeTe have been considered to support the threefold coordination of both the Ge and the Te atoms, namely 3(Ge):3(Te).…”

Section: Structural Considerations Of A-gete and C-getementioning

confidence: 99%

Raman scattering study of the a-GeTe structure and possible mechanism for the amorphous to crystal transition

Andrikopoulos¹,

Yannopoulos²,

Voyiatzis³

et al. 2006

J. Phys.: Condens. Matter

224

174

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We report on an inelastic (Raman) light scattering study of the local structure of amorphous GeTe films. A detailed analysis of the temperature-reduced Raman spectra has shown that appreciable structural changes occur as a function of temperature. These changes involve modifications of atomic arrangements such as to facilitate the rapid amorphous-to-crystal transformation, which is the major advantage of phase-change materials used in optical data storage media. A particular structural model, supported by polarization analysis, is proposed being compatible with the experimental data as regards both the structure of a-GeTe and the crystallization transition. The remarkable difference between the Raman spectrum of the crystal and the glass can thus naturally be accounted for.

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“…Short range order of amorphous Ge-Te alloys has been investigated for decades by diffraction and extended X-ray absorption fine structure (EXAFS) measurements [1][2][3][4][5][6][7][8]. Some early studies suggested the so called 3-3 model (both Ge and Te are threefold coordinated) but later the 4-2 model became prevailing.…”

Section: Introductionmentioning

confidence: 99%

Local order in binary Ge-Te glasses – An experimental study

Jóvári

Piarristeguy

Pradel

et al. 2019

Journal of Alloys and Compounds

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The structure of Ge x Te 100-x (x = 14.5, 18.7, 23.6) glasses prepared by twin roller quenching technique was investigated by neutron diffraction, X-ray diffraction and Ge-K-edge X-ray absorption spectroscopy measurements. Large scale structural models were obtained for each composition by fitting the experimental datasets in the framework of the reverse Monte Carlo technique. It was found that the majority of Ge and Te atoms satisfy the 8-N rule. Simulation results indicate that Ge-Ge bonding is not significant for x = 14.5 and 18.7. The shape and position of the first peak of the Ge-Ge partial pair correlation function evidence the presence of corner sharing tetrahedra already in compositions (x = 14.5 and 18.7) where 'sharing' of a Te atom by two Ge atoms could be avoided due to the low concentration of Ge.

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Structural analysis of amorphous Ge0.5Te0.5 by neutron diffraction

Cited by 32 publications

References 11 publications

In-situ crystallization of GeTe\GaSb phase change memory stacked films

In-situ crystallization of GeTe\GaSb phase change memory stacked films

Raman scattering study of the a-GeTe structure and possible mechanism for the amorphous to crystal transition

Local order in binary Ge-Te glasses – An experimental study

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