Temperature dependence of structural and optical properties of GeSbTe alloy thin films

Chabli, Amal; Vergnaud, C.; Bertin, F.; Gehanno, V.; Valon, B.; Hyot, Bérangère; Bechevet, B.; Burdin, M.; Muyard, D.

doi:10.1016/s0304-8853(02)00471-7

Cited by 13 publications

(11 citation statements)

References 6 publications

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“…On the basis of the XRD, TEM, and Raman analyses, we simulated the crystallization process of the amorphous region ͑25 nm thick͒ considering a planar a-c interface with an average growth rate of about 4 ϫ 10 −3 nm/ s and using the optical constant of the amorphous and crystalline GST phases extracted from Ref. 25. The growth rate used for the simulation has been compared to the value reported in a previous work by Kalb et al 26 He obtained his data by atomic force microscopy measurements on 30 nm of amorphous GST films deposited on Si by sputtering and annealed ex situ in the range of 120-150°C.…”

Section: Resultsmentioning

confidence: 99%

Crystallization of ion amorphized Ge2Sb2Te5 thin films in presence of cubic or hexagonal phase

Bastiani

Carria

Gibilisco

et al. 2010

Journal of Applied Physics

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The crystallization kinetics of amorphous Ge2Sb2Te5 (GST) thin films, generated by ion implantation, on top of crystalline GST, either in the cubic or hexagonal phase, was investigated by means of time resolved reflectivity measurements, x-ray diffraction, in situ transmission electron microscopy, and Raman analyses. The crystallization occurred at a lower temperature with respect to a fully amorphous film and in both cases the crystalline phase started growing at the underlying amorphous-crystalline (a-c) interface. However, it was not a solid phase epitaxial growth since cubic GST was always obtained, independent of the phase of the underlying crystal. We speculate that the a-c interface behaves as a continuous region of potential nucleation sites in the crystallization making the crystallization process more efficient.

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Section: Resultsmentioning

confidence: 99%

Crystallization of ion amorphized Ge2Sb2Te5 thin films in presence of cubic or hexagonal phase

Bastiani

Carria

Gibilisco

et al. 2010

Journal of Applied Physics

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“…Each of the atomic configurations of GST have different physical (optical, electrical, and mechanical) properties. [4] The crystalline phase is more reflective and up to three orders of magnitude more electrically conductive than the amorphous phase. [1] These differences in the physical properties between phases, in addition to the ability to retain either phase state for a long time at ambient temperatures, [5] have been utilized in technologies such as rewritable optical data storage (DVD-RW, Blu-ray RW) and nonvolatile electronic phase-change memories…”

Section: Doi: 101002/aelm201700079mentioning

confidence: 99%

Mixed‐Mode Electro‐Optical Operation of Ge₂Sb₂Te₅ Nanoscale Crossbar Devices

Rodriguez-Hernandez

Hosseini

Rı́os

et al. 2017

Adv Elect Materials

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The use of phase‐change materials for a range of exciting new optoelectronic applications from artificial retinas to ultrahigh‐resolution displays requires a thorough understanding of how these materials perform under a combination of optical and electrical stimuli. This study reports for the first time the complex link between the electronic and optical properties in real‐world crossbar nanoscale devices constructed by confining a thin layer of Ge2Sb2Te5 between transparent indium tin oxide electrodes, forming an optical nanocavity. A novel proof‐of‐concept device that can be operated by a combination of optical and electrical stimuli is presented, leading the way for the development of further applications based on mixed‐mode electro‐optical operation.

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“…Thermal boundary resistance between the GST layer and ZnS:SiO 2 capping/underlayer is not included in the model to reduce the mathematical complexity, but its influence is implicitly present through the large thicknesses of the capping and underlayers in the model. Absorption of the optical energy in the Si substrate and possible crystallization of the dielectric ZnS:SiO 2 layers 18 are not modelled in this work to reduce the mathematical complexity of the problem and is beyond the remit of this work. However, the effect of energy absorption in the Si substrate is expected to be small due to the relatively large thickness of the dielectric underlayer.…”

Section: Heat Flow and Crystallization Modelsmentioning

confidence: 99%

Crystallization of Ge2Sb2Te5 films by amplified femtosecond optical pulses

Liu

Aziz

Shalini

et al. 2012

Journal of Applied Physics

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The phase transition between the amorphous and crystalline states of Ge 2 Sb 2 Te 5 has been studied by exposure of thin films to series of 60 femtosecond (fs) amplified laser pulses. The analysis of microscope images of marks of tens of microns in size provide an opportunity to examine the effect of a continuous range of optical fluence. For a fixed number of pulses, the dependence of the area of the crystalline mark upon the fluence is well described by simple algebraic results that provide strong evidence that thermal transport within the sample is one-dimensional (vertical). The crystalline mark area was thus defined by the incident fs laser beam profile rather than by lateral heat diffusion, with a sharp transition between the crystalline and amorphous materials as confirmed from line scans of the microscope images. A simplified, one-dimensional model that accounts for optical absorption, thermal transport and thermally activated crystallization provides values of the optical reflectivity and mark area that are in very good quantitative agreement with the experimental data, further justifying the one-dimensional heat flow assumption. Typically, for fluences below the damage threshold, the crystalline mark has annular shape, with the fluence at the centre of the irradiated mark being sufficient to induce melting. The fluence at the centre of the mark was correlated with the melt depth from the thermal model to correctly predict the observed melt fluence thresholds and to explain the closure and persistence of the annular crystalline marks as functions of laser fluence and pulse number. A solid elliptical mark may be obtained for smaller fluences. The analysis of marks made by amplified fs pulses present a new and effective means of observing the crystallization dynamics of phase-change material at elevated temperatures near the melting point, which provided estimates of the growth velocity in the range 7-9 m/s. Furthermore, finer control over the crystallization process in phase-change media can be obtained by controlling the number of pulses which, along with the laser fluence, can be tailored to any medium stack with relaxed restrictions on the thermal properties of the layers in the stack. V C 2012 American Institute of Physics. [http://dx

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Temperature dependence of structural and optical properties of GeSbTe alloy thin films

Cited by 13 publications

References 6 publications

Crystallization of ion amorphized Ge2Sb2Te5 thin films in presence of cubic or hexagonal phase

Crystallization of ion amorphized Ge2Sb2Te5 thin films in presence of cubic or hexagonal phase

Mixed‐Mode Electro‐Optical Operation of Ge₂Sb₂Te₅ Nanoscale Crossbar Devices

Crystallization of Ge2Sb2Te5 films by amplified femtosecond optical pulses

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Temperature dependence of structural and optical properties of GeSbTe alloy thin films

Cited by 13 publications

References 6 publications

Crystallization of ion amorphized Ge2Sb2Te5 thin films in presence of cubic or hexagonal phase

Crystallization of ion amorphized Ge2Sb2Te5 thin films in presence of cubic or hexagonal phase

Mixed‐Mode Electro‐Optical Operation of Ge2Sb2Te5 Nanoscale Crossbar Devices

Crystallization of Ge2Sb2Te5 films by amplified femtosecond optical pulses

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Mixed‐Mode Electro‐Optical Operation of Ge₂Sb₂Te₅ Nanoscale Crossbar Devices