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Aluminum nitride (AlN) nanostructures are very attractive in various optoelectronic applications such as deep ultraviolet light emitting devices. The fabrication of these AlN nanostructures with good crystalline quality and compatibility in line with other micro-fabrication processes has significant importance for practical applications. AlN films of different thickness values were deposited via DC reactive magnetron sputtering over vertically aligned multiwalled carbon nanotube (CNTs) arrays to obtain AlN/CNTs vertically-aligned shell/core nanostructure assembly. Such hybrid nanostructures were characterized using scanning electron microscope, transmission electron microscope, X-ray diffraction, Raman spectroscopy and time-resolved photoluminescence spectroscope (TR-PL) techniques. The results indicated that AlN/CNTs have a nanorods structure morphology with good AlN crystalline quality. The PL measurements revealed a maximum increase in the luminescent intensity of the exciton band in case of AlN/CNTs with 600 nm thick AlN layer, which is many orders of magnitude higher than that of AlN film produced over silicon substrate. It is anticipated that synergistic effects of CNTs and AlN through an increase in the specific surface area and oxygen-induced defects cause enhancement in the photoluminescence properties, making these hybrid nanostructures a promising candidate for optoelectronic applications. [ABSTRACT FROM AUTHOR]

We report fabrication of nanostructured zinc oxide (ZnO) thin films with improved optical properties through electrochemical anodization. The ZnO films were produced over silicon substrates via radio-frequency (RF) plasma magnetron sputtering technique followed by electrochemical treatment in potassium sulfate solution. After electrochemical treatment, the effect of applied potential on the band gap emission behavior of ZnO films was investigated for the potential drop of 1.8, 2.4 and 3.0 V against reference electrode of Ag/AgCl/0.1 M KCl. Depending on these values, ZnO films with different degrees of nonporous morphology, improved structural quality and oxygen-rich surface chemistry were obtained. The treatment also resulted in enhancement of band gap emission from ZnO films with the degree of enhancement depending on the applied potential. As compared to the as-deposited films, a maximum increase in the photoemission intensity by more than 2.2 times was noticed. In this paper, any changes in the structure, surface chemistry and band gap emission intensity of the RF sputter deposited films, as induced by the anodization treatment at differential potential values, are discussed. [ABSTRACT FROM AUTHOR]

Abstract: ZnO films were deposited on Si substrate by RF-sputtering using titanium nitride (TiN) as buffer layer that was deposited at different thicknesses: 160 and 2290nm. Despite the lattice mismatch of up to 6.35% between ZnO and TiN, the ZnO films deposited on TiN buffer layers show enhanced near-band-edge photoluminescence (PL) emission at room temperature which is two times higher of magnitude than those grown directly on Si. The PL enhancement intensity, provided by TiN buffer introduction, is attributed to the improvement of ZnO crystalline quality and stoichiometry. The use of a good electrical conductor which has high thermal stability like TiN as buffer layer for the blue emission enhancement of ZnO would make it promising for optoelectronic applications. [Copyright &y& Elsevier]

Abstract: Zinc oxide (ZnO) nanostructures are very attractive in various optoelectronic applications such as light emitting devices. A fabrication process of these ZnO nanostructures which gives a good crystalline quality and being compatible with that of micro-fabrication has significant importance for practical application. In this work ZnO films with different thicknesses were deposited by RF-sputtering on vertically aligned multiwalled carbon nanotube (MWCNTs) template in order to obtain ZnO nanorods. The obtained hybrid structures (ZnO/MWCNTs) were characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and time resolved photoluminescence spectroscopy (PL). Results show that the ZnO/MWCNTs have a nanorod structure like morphology with a good crystalline quality of the deposited ZnO on the MWCNTs. PL measurements reveal an enhancement of the band edge signal of ZnO/MWCNTs which is three times of magnitude higher compared to the ZnO film deposited on silicon. Moreover, the intensity enhancement varies as function of the ZnO thickness. Such hybrid structures are promising for optoelectronic application, such as blue–violet sources. [Copyright &y& Elsevier]