Narrow Results

Emerging memory technologies promise new memories to store more data at less cost. On the other hand, the scaling of silicon-based chips approached its physical limits. Nonvolatile memory technologies, such as resistive random-access memory (RRAM), are trying to solve this problem. The fundamental study in RRAM devices still needs to be moved further. In this regard, conduction mechanism of RRAM is focused in this study. The RRAM conductance varies considerably depending on the material used in the dielectric layer and selection of electrodes. To formulate the conductance mechanism, new materials with notable conductivity such as graphene oxide (GO) sheets has been employed by researchers. In the GO-based RRAM, pristine of GO due to the presence of sp³-hybridized oxygen functional groups(hydroxyl) leads to electrically insulating layers in the device. However, by applying the voltage, the conductive path can be formed with the redox of GO layer in to graphene. This phenomenon is known as RRAM set process which can be explained due to the conversion of sp³ to sp² oxygen functionalities, which make the RRAM to move in to the ON state. Also, in this paper, variation of the ON state resistance by the voltage in the nondegenerate mode is described and the reset process by degeneracy variation is reported.

Calculations of chemical reactions between C₂₀, C₆₀, hydrogen and water molecules are carried out using the PM3 method. Reactions with a hydrogen release at room temperature and atmospheric pressure are identified by the Gibbs energy change. The hydrogen release can be raised by increasing the number of water molecules in chlorine-assisted decomposition of fullerenes. Calculations of the Gibbs energy of chemical reactions involving water molecules between two parallel curved graphene sheets are carried out using DFT with the functional UB3LYP. During pumping between plates of an electric capacitor designed from curved graphene sheets, the water vapor with the assistance of external illumination is enriched by electrically neutral hydroxyl groups (OH)⁰.

ZnO nanoparticles have been prepared by wet chemical method. The properties of the synthesized nanostructures are studied using X-ray diffraction, Transmission Electron Microscopy (TEM), Photoluminescence (PL), Ultraviolet-Visible absorption, Laser Raman and Fourier transform Infrared (FTIR) spectroscopy. The thermal decomposition is analyzed by Thermogravimetric (TG) and Differential Thermal Analysis (DTA). The influence of annealing on structural and optical properties of ZnO nanoparticles has been systematically investigated. The PL results demonstrated that the visible emission at 565 nm is associated with the combination of oxygen vacancies and OH group attached at the surface of ZnO nanoparticles. OH group is lessened from the surface of ZnO nanoparticles with annealing temperature and a blue-shift in visible emission peak is observed at 800°C annealing temperature.