Phase change memory materials–composition, structure, and properties

Frumar, M.; Frumarová, Božena; Wágner, T.; Hrdlicka, M.

doi:10.1007/s10854-007-9187-7

Cited by 22 publications

(9 citation statements)

References 22 publications

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“…• C) below the crystallization temperature, as determined by DSC and by the temperature dependence of electrical conductivity measurements [13,14], can increase the ordering of the film of Ge 2 Sb 2 Te 5 and lead to an increase of the number and size of individual nuclei embryos (Fig. 3).…”

Section: Discussionmentioning

confidence: 99%

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On the atomic structure of thin amorphous Ge–Sb–Te films

Frumar

Kohoutek

Přikryl

et al. 2009

Physica Status Solidi (b)

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The structure of thin films of Ge2Sb2Te5 was studied by high‐resolution transmission electron microscopy (HRTEM) and by X‐ray diffraction (XRD). The as‐evaporated films prepared by flash evaporation were amorphous. Nearly, all the atoms were randomly distributed but even in as‐evaporated films small areas with some ordering were noticeable. The number and size of the ordered areas increased with thermal treatment of films to temperatures ∼80 °C, i.e., ∼70 °C below the crystallization temperature of amorphous Ge2Sb2Te5. After thermal treatment, small embryos of nucleation centers (size <8 nm) were formed. According to XRD measurements the films as a whole were still fully amorphous. The crystallite model of the structure of amorphous solids is then partly valid, at least for Ge2Sb2Te5. We expect that it can be applied also for other Ge–Sb–Te‐based films, as well as for the other amorphous chalcogenides. The possible impact of the formation of nucleation “embryos” on storage time of data in optical and electrical phase‐change memory materials and devices is discussed.

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Section: Discussionmentioning

confidence: 99%

“…• C) of Ge 2 Sb 2 Te 5 thin films [13][14][15]. The time period between the two measured temperatures was 5 min, i.e., the heating rate between the two steps was 2…”

Section: Methodsmentioning

confidence: 99%

On the atomic structure of thin amorphous Ge–Sb–Te films

Frumar

Kohoutek

Přikryl

et al. 2009

Physica Status Solidi (b)

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“…the development of amplifiers and laser sources, optical sensors and all-optical processing components based on non-linear properties [1][2][3][4][5]. In this frame, a special chalcogenide glasses class, namely gallium lanthanum sulphide (GLS), has been evidenced (in particular when doped with rare earth elements) as an attractive non-toxic alternative to arsenic-based glasses, with optical transparency from the visible to infrared wavelengths, thermal stability, high refractive indices, high rare-earth solubility, high transition temperature and large photoinduced effects [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Plasma diagnostics in pulsed laser deposition of GaLaS chalcogenides

Pompilian¹,

Gurlui²,

Němec³

et al. 2013

Applied Surface Science

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The aim of this work is to characterize the ejection plume obtained by laser ablation of GaLaS (GLS) samples in order to better understand the ablation phenomena for optimizing the pulsed laser deposition of chalcogenide thin films. The dynamics of the plasma between target and substrate was investigated through timeand space-resolved optical emission spectroscopy. High-resolution optical spectra have been recorded in the UV-VIS range using a 500-mm focal length monochromator and a fast gate ICCD camera. From the space-time evolution of the optical signals, the velocities of various species (including neutrals and ions) have been derived. Using the relative intensity method, the space-and time-evolution of the excitation temperature and electronic density have been determined. A complex behavior of the laser ablation plasma has been revealed.

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“…As shown recently by Frumar et al [18] the crystalline state in these phase-change materials is highly imperfect, with high amount of defects integrated into the structure. This means that in our model the switching back to the crystalline state is in fact a transition to a highly defective crystalline state.…”

Section: Discussionmentioning

confidence: 84%