Influence of dielectric capping layers on the crystallization kinetics of Ag5In6Sb59Te30 films
Njoroge, W. K.
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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 Ag5In6Sb59Te30films 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 Ag5In6Sb59Te30films, 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.