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Ovonic threshold switching in polycrystalline zinc telluride thin films deposited by RF sputtering
摘要： Chalcogenide materials of the amorphous phase with low band gaps were reported to show Ovonic threshold switching (OTS), making them suitable for selection devices in cross-point memory arrays. Herein, we report that ZnTe films with polycrystalline structures show OTS behavior. Nearly stoichiometric ZnTe thin films were deposited by an RF sputtering method. X-ray diffraction analysis indicated that the films were polycrystalline. The optical band gaps of the ZnTe films were estimated as 2.2 eV from UV-visible spectroscopy transmittance measurements. Photoluminescence measurements indicated the existence of deep-level defects in the ZnTe thin films. Although these ZnTe films have a polycrystalline structure with a relatively high band gap, I-V profiles show OTS characteristics, with a selectivity of over 104, fast threshold switching time in the sub-10 ns scale, and thermal stability up to 400°C. ZnTe also shows switching endurance for more than 109 cycles without Vth drift, maintaining its selectivity of 104. Thus, we improved the threshold switching characteristics by using a wide-band-gap and polycrystalline-structured ZnTe-based chalcogenide material. Post-annealing experiments indicated that the thermal budget of the ZnTe thin film was sufficient for stacked cross-point array structures, thereby overcoming a previous limitation of chalcogenide switching materials. This material is promising for application in high-density cross-point memory arrays as the selection device.
关键词： crystalline,ovonic threshold switching,selection device,thermal stability,zinc telluride
更新于2025-09-19 17:15:36
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Ultrasonic and microwave assisted extraction as rapid and efficient techniques for plant mediated synthesis of quantum dots: green synthesis, characterization of zinc telluride and comparison study of some biological activities
摘要： In this study, a simple, rapid, and efficient plant-mediated green approach was presented for the synthesis of stable and ultra-small zinc telluride quantum dots (ZnTe QDs) using the aqueous extract of the Ficus johannis plant. Two modern techniques, namely ultrasonic and microwave techniques, were applied to prepare the plant extracts, which were then used as stabilizing precursors in the synthesis of ZnTe QDs. The synthesized samples were characterized via different techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible absorption, photoluminescence and Fourier transform infrared spectroscopy. The TEM images confirmed the formation of ultra-small nanoparticles with an average size of 8 nm. According to the optical characterization, a wide absorption band around 390 nm and an intense emission peak at 463 nm clarified the successful synthesis of ZnTe QDs. After synthesis and characterization, the antioxidant, antimicrobial, and antifungal potentials of the as-prepared QDs as well as the plant extracts were examined by different tests, comparatively. In addition, the determination of the total phenolic and flavonoid contents of the as-prepared samples was carried out. Moreover, the toxicity of the samples was investigated by Artemia uramiana from their brine shrimp lethality potentials. In the cytotoxicity tests, the inhibition of root growth was considered as an indicator to evaluate the cytotoxicities of the samples.
关键词： Ultrasonic,quantum dots,microwave,biological activities,extraction,green synthesis,zinc telluride
更新于2025-09-11 14:15:04