Submicron periodic lattices are formed at the surface of phase-change-memory film materials based on the complex chalcogenide Ge_2Sb_2Te_5 when exposed to nanosecond laser pulses. The geometric characteristics and structural properties of laser-induced lattices are studied by optical and atomic-force microscopies and Raman spectroscopy. It is shown that, at appropriately chosen parameters of exposure to laser radiation, it is possible to implement periodic modulation of the refractive index in the structures formed. Modulation is due to the postexposure solidification of grating ridges and valleys in different phase states, whose dielectric constants widely differ from each other. In the vicinity of the maxima of the wavy structure, the amorphous state is mainly formed, whereas in the region of minima, the Ge_2Sb_2Te_5 structure corresponds mainly to the crystalline phase.
This paper describes the processes of preparing solutions of binary vitreous semiconductor materials As 2 X 3 (X = S, Se) and fabricating thin films based on them by spin coating. The initial materials are synthesized using semiconductor purity grade solvents by the direct synthesis in pre-vacuumed quartz vials at a maximum temperature of 750ºС and identified by the authors as glass. The obtained amorphous thin films are proven to have an island morphology. The thickness of the As 2 S 3 film can vary in the range of 200 nm (at an average roughness of 0.7 nm) to 2.5 μm (at an average roughness of 100 nm). The thickness of the As 2 Se 3 film can vary in the range of 200 nm (at an average roughness of 8 nm) to 3 μm (at an average roughness of 200 nm). The optical characteristics of thin films are also studied, in particular optical transmission in the visible spectrum. The band gap of the obtained films is determined by employing a Tauc plot. The findings of the experiment are compared with the literature data.
Исследованы температурные зависимости удельного сопротивления и вольт-амперных характеристик тонких пленок материалов фазовой памяти на основе халькогенидных полупроводников квазибинарного разреза GeTe-Sb2Te3: Ge2Sb2Te5, GeSb2Te4 и GeSb4Te7. Изучено влияние изменения состава по линии квазибинарного разреза на электрофизические характеристики и механизмы переноса тонких пленок. Установлено наличие трех диапазонов с различной зависимостью между током и напряжением. Оценено положение и концентрация энергетических уровней, контролирующих перенос носителей. Полученные результаты показывают, что электрофизические свойства тонких пленок могут существенно изменяться при движении вдоль линии квазибинарного разреза GeTe-Sb2Te3, что важно для целенаправленной оптимизации технологии фазовой памяти. DOI: 10.21883/FTP.2017.02.44096.8270
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