Structure and properties of nanostructured ZnO arrays and ZnO/Ag nanocomposites fabricated by pulsed electrodeposition

We investigate the structure, surface morphology, and optical properties of nanostructured ZnO arrays fabricated by pulsed electrodeposition, Ag nanoparticles precipitated from colloidal solutions, and a ZnO/Ag nanocomposite based on them. The electronic and electrical parameters of the ZnO arrays and ZnO/Ag nanocomposites are analyzed by studying the I–V and C–V characteristics. Optimal modes for fabricating the ZnO/Ag heterostructures with the high stability and sensitivity to ultraviolet radiation as promising materials for use in photodetectors, gas sensors, and photocatalysts are determined.     

Electrodeposited zinc oxide arrays with the moth-eye effect

The materials of modern photovoltaic cells exhibit significant light reflection which is avoided using antireflective coatings. The possibility of fabricating antireflective coatings such as nanoscale zinc oxide arrays with a parabolic profile by pulsed electrochemical deposition from aqueous electrolytes is shown for the first time. The effect of the deposition conditions on the optical properties of oxide arrays is studied using spectrophotometry. The structural characteristics are analyzed by X-ray diffraction data. The morphology of the grown arrays is determined by atomic-force microscopy. Optimization of the pulsed electrodeposition conditions allows correction of the parabolic nanonipple sizes, thus providing the fabrication of antireflective coatings based on electrodeposited zinc oxide arrays with the moth-eye effect, applicable to photovoltaic cells.     

On Controlling the Hydrophobicity of Nanostructured Zinc-Oxide Layers Grown by Pulsed Electrodeposition

The possibility of fabricating highly hydrophobic nanostructured zinc-oxide layers by the inexpensive method of pulsed electrodeposition from aqueous solutions without water-repellent coatings, adapted for large-scale production, is shown. The conditions of the deposition of highly hydrophobic nanostructured zinc-oxide layers exhibiting the “rose-petal” effect with specific morphology, optical properties, crystal structure and texture are determined. The grown ZnO nanostructures are promising for micro- and nanoelectronics as an adaptive material able to reversibly transform to the hydrophilic state upon exposure to ultraviolet radiation.     

Microwave Giant Magnetoresistance in [CoFe/Cu]n Superlattices with Record-High Magnetoresistance

Technical Physics Letters - Microwave giant magnetoresistance in [CoFe/Cu]n nanostructures is studied in the millimeter-wave range. Measurements are preformed for superlattices with the maximum...     

Tunneling effects in tilted magnetic fields in n-InGaAs/GaAs structures with strongly coupled double quantum wells

The effects of tunneling between two parallel two-dimensional electron gases in n-InGaAs/GaAs nanostructures with strongly coupled double quantum wells with a change in the in-plane component of a tilted magnetic field (up to B _‖ = 9.0 T) in the temperature range T = 1.8–70.0 K are investigated. A nonmonotonic temperature dependence of the inverse quantum lifetime τ _q ^? (T) is obtained from analysis of the dependence of the longitudinal resistance on the parallel component of the tilted magnetic field at fixed temperatures, ρ _xx (B _‖, T). The quadratic portion of this dependence is found to be due to the contribution of inelastic electron-electron scattering. The decrease in the inverse quantum lifetime τ _q ^? (T) at T > 0.1T _F cannot be described within known theories; it seems, it is not related to the processes of electron momentum relaxation.     

Prospects for the pulsed electrodeposition of zinc-oxide hierarchical nanostructures

Studies into the effect of the conditions of pulsed electrodeposition upon the structural and sub-structural parameters, morphology, and optical properties of ZnO-crystallite arrays make it possible to establish those parameters optimal for the formation of ZnO nanorods oriented normally to the substrate surface. These parameters are as follows: an electrolyte temperature of 70–85°C, duty cycle of 40%, and a pulse-repetition frequency of 2 Hz. The nanorod dimensions can be varied by heating or cooling the electrolyte within the above-indicated limits; as a result, small-sized nanorods can be electrically deposited on the surface of larger nanorods to form hierarchical nanostructures. By varying the duty cycle, it is possible to modify the surface morphology of the arrays up to the formation of mesoporous ZnO networks. In combination with ZnO nanorods, such networks are capable of forming hierarchical nanostructures with large specific areas.     

Thermoelectric textile devices with thin films of nanocellulose and copper iodide

Owing to the rapid development of wearable electronics and smart textiles, demands for flexible and wearable thermoelectric (TE) devices, which can generate electricity in a ubiquitous, unintermittent and noiseless way for on-body applications are growing rapidly. Due to the inherent flexibility and wearability features, textile-based thermoelectric generators (TEGs) possess significant potential for biomedical and consumer health and safety applications. In this study, using commercial cotton fabric, we created efficient thermoelectric (TE) textile that, unlike analogs, is based on thin-film composite of biocompatible semiconductor copper iodide (CuI) and biodegradable polymer nanocellulose (NC_p) obtained by processing a widespread plant common reed. The CuI films with average thickness 10 µm were deposited via low-temperature aqueous cheap, facile, and scalable fabrication technique Successive Ionic Layer Adsorption and Reaction (SILAR). The NC_p sublayer made it possible to fabricate thin-film ohmic contacts through vacuum deposition of chromium on the nanostructured CuI film in the TE textile. The topping of CuI film with NC_p layer improved durability and wear resistance of the wearable thermoelectric module fabricated with this TE textile. The developed TE module has shown output power density 44 µW/cm² at temperature gradient 50 K that is among the best currently known results for solid miniature flexible and fabric-based TEGs.