We report the effects of bottom electrode shapes on resistive random-access memory (RRAM) devices composed of Nb (bottom electrode)/NiO (dielectric)/Nb (top electrode) structures. By adopting a nano-fabrication process using an anodic aluminum oxide (AAO) nanotemplate, a well-aligned Nb nanopin array bottom electrode was formed on the surface of a Si substrate. For comparison, a Nb thin film was employed as a different type of bottom electrode. Then, a NiO thin film dielectric was prepared on both the Nb bottom electrodes via a spin coating method, followed by Nb sputtering for the Nb top electrode. Both the RRAM devices with Nb nanopin and thin film bottom electrodes exhibited typical unipolar resistive switching behavior. However, a lower SET/RESET voltage was observed for the Nb nanopin electrode compared to the Nb thin film electrode by virtue of an enhanced electric field induced by the nanopin-shaped electrode. More significantly, on the basis of endurance and retention characteristics, the Nb nanopin electrode played a key role in minimizing the dispersion of the low- and high-resistance state currents and the variation in the SET/RESET voltage by developing more-concise conducting filaments in the conducting path. Therefore, we foresee that this approach can provide an insight into the optimal design of RRAM devices.

PMMA/PEG and PMMA/PEG doped with SiO₂, TiO_2, and Al₂O₃ were fabricated using the solution-casting technique. The composites were characterized by X-ray diffraction and scanning electron microscopy (FE-SEM), which revealed that the amorphous nature of PMMA/PEG blend doped with Al₂O₃ was hindered by the crystalline nature of those doped with SiO₂ and TiO₂. The absorption of PMMA/PEG blend doped with Al₂O₃ is higher, band gap energies were decreased from 4.90 eV for PMMA/PEG blend to 4.03 eV, 3.09 eV, and 2.09 eV for SiO₂, TiO₂, and Al₂O₃ doped PMMA/PEG blend, respectively. The dielectric constant, ε′ has a high value (2 × 10⁴) for samples PMMA/PEG and SiO₂/PMMA/PEG. While dielectric loss \(\left( {\varepsilon ^{{\prime \prime }} } \right)\)-values decreased to < 100 for TiO₂/PMMA/PEG and Al₂O₃/PMMA/PEG. Further, the fabricated composite SiO₂/PMMA/PEG led to improvement the optical and dielectric properties compared with PMMA/PEG for optoelectronic such as manufacturing of optical fiber cables application. The results show TiO₂/PMMA/PEG and Al₂O₃/PMMA/PEG are multifunctional can be used as low-permittivity nanodielectric and substrates to design the next generation of flexible electronic devices.

We investigated Al-doped ZnO nanowire gas sensors with various Al-doping ratios (0–6%) on sapphire substrates prepared by step edge decoration using pulsed layer deposition. High quality ZnO nanowires exhibited a diameter of about 20 nm and a regular interval of about 80 nm on sapphire substrates. For the Al doping of 3%, we obtained the highest sensitivity of about 170 for the ethanol concentration of 200 ppm. The highest sensitivity was obtained by a reduction in the lowest resistivity resulting from the optimum Al doping of 3% although the highest resistivity of the Al-doped ZnO nanowires was reduced.