Amorphous-crystal transition of Ge-Sb-Te thin films using resistivity measurements

J.ROCCA; M. FONTANA; B. ARCONDO; M.MOLINA RUIZ; J. RODRIGUEZ VIEJO

La Plata

Congreso; HK2011, Humboldt Kolleg (Argentine- Germany: A century of scientific Cooperation in Physics); 2011

Phase change materials show unique properties that have motivated important technogical aplications. Ge-Sb-Te is one of the most significant systems that exhibits these properties. GeSbTe alloys are employed in optical data storage (DVD technologies) and are candidates for future electronic storage application.In this work, films of compositions Ge13Sb5Te82 (atomic %) were obtained by pulsed laser deposition, using a Nd:YAG laser (λ = 266 nm). Atomic force microscopy (AFM) was employed to characterize the films thickness.The crystallization of the Ge13Sb5Te82 thin film was studied using the temperature dependence of sheet resistance measurements and by means of the nano-calorimetry technique at ultrafast heating rates (5x104 K/s). The crystallization temperature is determined in both measurements. In the resistance measurements, the films were put into a conventional electric furnace in vacuum upon a heating rate about 1.8 K/m. The value of the resistance falls three orders of magnitude in a small temperature range (400-440 K). In the nano-calorimetry measurements the onset temperature of the transformation is about 520 K. The crystallization products have been characterized by X-ray diffraction with Cu(Ka) radiation. These results are compared with those obtained in a previous work for amorphous samples that were rapidly quenched from the liquid state.