We present a systematic study of the growth of hexagonal ZnO nanotube arrays using a solution chemical method by varying the growth temperature (<100 C), time and solution concentration. A piezoelectric nanogenerator using the as-grown ZnO nanotube arrays has been demonstrated for the first time. The nanogenerator gives an output voltage up to 35 mV. The detailed profile of the observed electri...

We report the fabrication of heterostructure white light-emitting diode (LED) comprised of n-ZnO nanotubes (NTs) aqueous chemically synthesized on p-GaN substrate. Room temperature electroluminescence (EL) of the LED demonstrates strong broadband white emission spectrum consisting of predominating peak centred at 560 nm and relatively weak violet-blue emission peak at 450 nm under forward bias....

We explore the generalization to the helical case of the classical Ewald method, the harbinger of all modern self-consistent treatments of waves in crystals, including ab initio electronic structure methods. Ewald-like formulas that do not rely on a unit cell with translational symmetry prove to be numerically tractable and able to provide the crucial component needed for coupling objective mol...

The photoresponse behavior of one-dimensional ZnO nanowires (NWs) and nanotubes (NTs) grown on ITO-coated glass substrates via a wet-chemical route was investigated. The photoluminescence spectra exhibited a decrease in the deep-level intensity, indicating that the oxygen defects and impurities are occupied by the presence of N ions in the ZnO NT matrix after a nitrogen plasma treatment. I-V te...

TiO2 nanotube (NT) arrays were fabricated on the surface of n-GaN through a liquid-phase conversion process using ZnO nanorods (NRs) as a template for high-efficiency InGaN/GaN multiple quantum well (MQW) vertical light-emitting diodes (VLEDs). The optical output power of the VLEDs with TiO2 NTs was remarkably enhanced by 23% and 189% at an injection current of 350 mA compared to those of VLEDs...

Large-area, highly ordered ZnO micropores-arrays consisting of ZnO nanotubes delimited by ZnO nanorods have been successfully fabricated and tested for protein sensing applications. ZnO seed layers have been deposited by Metal Organic Chemical Vapour Deposition and readily patterned by Colloidal Lithography to attain ZnO nanorods growth at selective sites by Chemical Bath Deposition. The used s...

Dye-sensitized solar cells based on ordered arrays of polycrystalline ZnO nanotubes, 64 mum in length, are shown to exhibit efficient electron collection over the entire photoanode array length. Electrochemical impedance spectroscopy, open-circuit photovoltage decay analysis, and incident-photon-to-current efficiency spectra are used to quantify charge transport and lifetimes. Despite the relat...

ZnO nanotubes and nanorods grown on gold thin film were used to create pH sensor devices. The developed ZnO nanotube and nanorod pH sensors display good reproducibility, repeatability and long-term stability and exhibit a pH-dependent electrochemical potential difference versus an Ag/AgCl reference electrode over a large dynamic pH range. We found the ZnO nanotubes provide sensitivity as high a...

In this article, the electroluminescence (EL) spectra of zinc oxide (ZnO) nanotubes/p-GaN light emitting diodes (LEDs) annealed in different ambients (argon, air, oxygen, and nitrogen) have been investigated. The ZnO nanotubes by aqueous chemical growth (ACG) technique on p-GaN substrates were obtained. The as-grown ZnO nanotubes were annealed in different ambients at 600°C for 30 min. The EL i...

We report on the growth of high-aspect-ratio (approximately > 300) zinc sulfide nanotubes with variable, precisely tunable, wall thicknesses and tube diameters into highly ordered pores of anodic alumina templates by atomic layer deposition (ALD) at temperatures as low as 75 degrees C. Various characterization techniques are employed to gain information on the composition, morphology and crysta...