Influence of dielectric capping layers on the crystallization kinetics of Ag5In6Sb59Te30 films

Abstract

AgInSbTe alloys are attractive storage materials for phase change recording utilizing both optical and electronic contrast. The demand to decrease the thickness of such storage layers increases the significance of the surrounding dielectric layers, which can have a profound impact on the crystallization process. Hence we have investigated the influence of different capping layers on the crystallization kinetics of Ag5In6Sb59Te30 films by measuring the electrical resistivity of the films as a function of temperature employing the van der Pauw method. While the phase transition temperature was found to only increase slightly for capped Ag5In6Sb59Te30 films, a profound impact on the activation barrier for crystallization was observed. Activation energies of 2.39±0.10eV and 3.24±0.12eV were determined for films capped with 5nm of ZnS-SiO2 and Si3N4, respective1y, in comparison with a value of 3.03±0.17eV for an uncapped film. Additional stress measurements reveal that this change in activation barrier is not caused by stresses induced by the dielectric films but must rather be due to the different activation barriers for heterogeneous nucleation at the different interfaces. In the amorphous state the temperature dependence of the sheet resistance follows an activation-type relation, where the activation energy is not affected by the capping layer.

Crystal growth within a phase change memory cell

“…This transition from super-cooled liquid to the glass state occurring at very high temperatures could be due to the very fast quench rates in our experiment. Other aspects, such as being in a confined cell and the subsequent impact of stress, and other interfacial effects could also influence this behaviour 21,23 .…”

“…This also enables measurement on the melt-quenched phase directly in the environment in which the material is going to be used. Note that the interface and stress conditions will be substantially different in this case, and this could also influence the crystallization dynamics significantly [21][22][23] . In a PCM cell, a layer of crystalline phase change material is sandwiched between two electrodes.…”

Disorder‐Induced Localization in Crystalline Pseudo‐Binary GeTe–Sb2Te3 Alloys between Ge3Sb2Te6 and GeTe

“…It has already been demonstrated [ 6,[22][23][24] that heating experiments such as those presented in Figure 1 can readily characterize the crystallization and annealing behavior of phase-change alloys: Starting with an initially as-deposited amorphous fi lm at room temperature, the sheet resistance of the fi lm is monitored while the fi lm is heated and subsequently cooled. The data depicted in Figure 1 were recorded using the following thermal treatment: 1) Heating up to 350 °C (5 K min −1 ); 2) Annealing at 350 °C for 30 min; 3) Cooling down to room temperature.…”

Influence of capping layers on the crystallization of doped SbxTe fast-growth phase-change films

“…24 Consequently, several properties of the phase-change layer including crystallization are significantly altered by the capping layers. [24][25][26][27][28] Therefore, the combination of the phasechange film and capping layers has to be considered, and improving understanding of the influence of capping layers on the crystallization kinetics of the phase-change film becomes vital in order to optimize the disk characteristics.…”

“…However, transmittance measurements or other techniques [26][27][28][29][30][31][32][33] generally used, such as differential scanning calorimetry, x-ray diffraction, electrical ͑resistance͒ measurements, and reflectance measurements, provide information only on the overall crystallization process, that is actually an interplay of both nucleation and growth processes. In contrast, transmission electron microscopy ͑TEM͒ is capable of providing separate information on nucleation and growth parameters.…”