Atomic force microscopy measurements of crystal nucleation and growth rates in thin films of amorphous Te alloys

Kalb, Johannes; Spaepen, Frans; Wuttig, Matthias

doi:10.1063/1.1764591

Cited by 174 publications

(134 citation statements)

References 20 publications

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“…15). As DGo0.18 eV is much lower than E a E3 eV in the glass state below 534 K, the observed Arrhenius behaviour shows that also in the melt-quenched state in memory cells the activation energy for diffusion controls the temperature dependence of the growth velocity 34,35 . It is also worth noting that we do not find sufficient evidence of a breakdown of the Stokes-Einstein relation between diffusivity and viscosity, which would introduce an exponent xo1 for the viscosity term Z in equation (1) 36 (Supplementary Note 5).…”

Section: Discussionmentioning

confidence: 99%

Crystal growth within a phase change memory cell

2014

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In spite of the prominent role played by phase change materials in information technology, a detailed understanding of the central property of such materials, namely the phase change mechanism, is still lacking mostly because of difficulties associated with experimental measurements. Here, we measure the crystal growth velocity of a phase change material at both the nanometre length and the nanosecond timescale using phase-change memory cells. The material is studied in the technologically relevant melt-quenched phase and directly in the environment in which the phase change material is going to be used in the application. We present a consistent description of the temperature dependence of the crystal growth velocity in the glass and the super-cooled liquid up to the melting temperature.

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Section: Discussionmentioning

confidence: 99%

Crystal growth within a phase change memory cell

2014

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“…As reported, 4,21 a ജ 0 and m = 0.5 for diffusion-controlled growth, while m = 1 for interfacecontrolled growth and the interface-controlled growth for GST has been proved. [10][11][12] Unfortunately, we cannot determinate whether N doping changes the type of the growth of GeSbTe. But if the type of growth was not changed, the value of m will still be 1.…”

Section: Methodsmentioning

confidence: 99%

“…The JMAK parameters such as Avrami coefficient, activation energy, etc. have been investigated mainly through microscope observation [10][11][12][13][14] or the optical measurement. 1-4 The resistivity measurement was also used to get information about the crystallization processes.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, a considerable number of studies for the kinetics of amorphous-crystalline transformation in phase-change media have been done. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Oshima, 1 Jeong et al, 2 Weidenhof et al, 3 Ruitenberg et al, 4 and Laine et al,5 reported that the crystallization behaviors of the GeSbTe films in isothermal condition satisfy the Johnson-Mehl-Avrami-Kolmogrov ͑JMAK͒ equation f =1 − exp͑−kt n ͒, where f is crystallinity, n is the Avrami coefficient, and k is an effective rate constant describing both the nucleation and growth. The JMAK parameters such as Avrami coefficient, activation energy, etc.…”

Section: Introductionmentioning

confidence: 99%

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Study on the crystallization by an electrical resistance measurement in Ge2Sb2Te5 and N-doped Ge2Sb2Te5 films

Zhu

et al. 2007

Journal of Applied Physics

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An electric resistance measurement was used to study the crystallization process of Ge 2 Sb 2 Te 5 ͑GST͒ and N-doped Ge 2 Sb 2 Te 5 ͑N-GST͒ films. The relation between conductivity and annealing time was investigated and the crystallization parameters were determined directly by resistance measurement during isothermal crystallization process in the amorphous GST and the N-GST films. The results show that the crystallization processes in both GST and N-GST films are layer by layer. Their conductivities satisfy the equation = c − ͑ c − a ͒exp͑−kt n ͒, at t Ͼ , where is a temperature-dependent time in the process of crystallization. The activation energy for crystallization of amorphous GST films was 2.11± 0.18 eV and the Avrami coefficient was between 2 to 4, in close agreement with previous studies using different techniques. After N doping the Avrami coefficient decreased, while the activation energy increased. The formation of a strain induced by the distortion of unit cell after N doping was used to explain the observed results.

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“…Chalcongenide phase-change materials are extensively used as the optical and nonvolatile electrical data storage media due to the apparent difference in optical reflectivity and electrical resistivity between the crystalline and amorphous state [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. For optical data storage, the recording is achieved by forming amorphous marks on a crystalline base with a focused laser beam.…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of thermal properties of Ag8In14Sb55Te23 phase-change memory materials

et al. 2008

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The dependence of thermal properties of Ag 8 In 14 Sb 55 Te 23 phase-change memory materials in crystalline and amorphous states on temperature was measured and analyzed. The results show that in the crystalline state, the thermal properties monotonically decrease with the temperature and present obvious crystalline semiconductor characteristics. The heat capacity, thermal diffusivity, and thermal conductivity decrease from 0.35 J/g K, 1.85 mm 2 /s, and 4.0 W/m K at 300 K to 0.025 J/g K, 1.475 mm 2 /s, and 0.25 W/m K at 600 K, respectively. In the amorphous state, while the dependence of thermal properties on temperature does not present significant changes, the materials retain the glass-like thermal characteristics. Within the temperature range from 320 K to 440 K, the heat capacity fluctuates between 0.27 J/g K and 0.075 J/g K, the thermal diffusivity basically maintains at 0.525 mm 2 /s, and the thermal conductivity decreases from 1.02 W/m K at 320 K to 0.

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Atomic force microscopy measurements of crystal nucleation and growth rates in thin films of amorphous Te alloys

Cited by 174 publications

References 20 publications

Crystal growth within a phase change memory cell

Crystal growth within a phase change memory cell

Study on the crystallization by an electrical resistance measurement in Ge2Sb2Te5 and N-doped Ge2Sb2Te5 films

Temperature dependence of thermal properties of Ag8In14Sb55Te23 phase-change memory materials

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