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Unipolar Nonvolatile Resistive Switching in Pt/MgO/Ta/Ru Structures Deposited by Magnetron Sputtering
摘要： The recent realization of memristors, nanodevices exhibiting non-volatile resistive switching, has sparked tremendous interest for applications in fields such as nonvolatile memories. Here we report unipolar resistive switching in Pt/MgO/Ta/Ru structures, with an oxide barrier thickness of only 15 nm. No electroforming process was required to achieve resistive switching and an ohmic conduction mechanism is associated with the ON state. We observed an inverse dependence of the ON state resistance on the SET current compliance and average values of 1.61 V and 1.38 V for the SET and RESET voltages, respectively. We show the stability of the switching for over 40 cycles and a clear separation of the ON (101 Ω) and OFF (102 Ω) states during at least 104 s.
关键词： Memristors,Magnetron Sputtering,Magnesium Oxide,Resistive Switching
更新于2025-09-04 15:30:14
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Bandgap bowing in crystalline (ZnO) <sub/> 1? <i>x</i> </sub> (GaN) <sub/><i>x</i> </sub> thin films; influence of composition and structural properties
摘要： Thin films of (ZnO)1?x(GaN)x with an optical bandgap between 3.3 and ～2.4 eV at room temperature for 0 ≤ x ≤ 0.2 have been grown by magnetron sputtering on (0001)-sapphire substrates. A strong dependence of the bandgap shrinkage on x for low values (x ≤ 0.07) not previously reported enables bandgap-tuned films of high crystal quality with limited distortion of the ZnO matrix suitable for optoelectronic applications. X-ray diffraction, transmission electron microscopy and Rutherford backscattering spectrometry all show a single phase and highly crystalline films. The a- and c-lattice constants are found to be 3.252 and 5.224 ? for x = 0.15, i.e. larger than that predicted by Vegard’s law. The films are highly c-axis oriented and exhibit a good heteroepitaxial relationship with the sapphire substrate, growing predominantly with aligned domains. A distinct shift in optical absorption is attributed to a shift in the bandgap, where compositions of x = 0.07 to x = 0.2 all result in bandgaps around or below 2.5 eV, while a lower GaN content increases the optical bandgap towards that of ZnO. This strong dependence of the bandgap shrinkage on x for low values (x ≤ 0.07) enables bandgap-tuned films of high crystal quality with limited distortion of the ZnO matrix.
关键词： magnetron sputtering,bandgap bowing,ZnO,GaN,alloy
更新于2025-09-04 15:30:14
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Investigation of Interface Diffusion in Sputter Deposited Gd0.1Ce0.9O1.95 Thin Buffer Layers on Y-Stabilized Zirconia Crystalline Substrates for Solid Oxide Cells Applications
摘要： This paper presents the results concerning the investigation of the morphological and structural properties of Gd0.1Ce0.9O1.95 layers deposited on crystalline (111) YSZ subtrates by RF magnetron sputtering. Room temperature as-grown samples have been annealed at different temperatures from 600°C to 1300°C. Atomic Force Microscopy analysis shows an increase in the average grain size dimensions with increasing annealing temperatures. X-Ray Diffraction measurements indicates a preferential growth of the grains along the (111) direction with a decrease in the evaluated c-axis as a function of the annealing temperature, probably related to an over-oxidation of the samples. X-Ray Reflectivity studies, performed on thin layers annealed at temperatures from 700-1000°C, points out the presence of zones with different densities and roughness at the layer/substrate interface and at the layer/vacuum surface. The behaviour of these zones as a function of temperature has been investigated. The obtained results seem to exclude the presence of consistent inter-diffusion phenomena at the GDC/YSZ interface.
关键词： Solid oxide cells,X-ray reflectivity,Reciprocal space map,RF magnetron sputtering,Yttrium stabilized Zirconia,Gadolinium doped Ceria,Interdiffusion
更新于2025-09-04 15:30:14