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In this work, we described the variations in the defect energy levels of four different ZnO morphologies, namely nanoribbons, nanorods, nanoparticles, and nanoshuttles. All the ZnO morphologies were grown on a seeded 4% Boron-doped p-type silicon (p-Si) wafer by using two different synthesis techniques, which are chemical bath deposition and microwave-assisted methods. The defect energy levels were analyzed by using the Deep-Level Transient Spectroscopy (DLTS) characterization method. The DLTS measurements were performed in the 123 K to 423 K temperature range. From the DLTS spectra, we found the presence of different trap-related defects in the synthesized ZnO nanostructures. We labeled all the traps related to the four different ZnO nanostructures as P1, P2, P3, P4, and P5. We discussed the presence of defects by measuring the activation energy (Ea) and capture cross-section (α). The lowest number of defect energy levels was exhibited by the ZnO nanorods at 0.27 eV, 0.18 eV, and 0.75 eV. Both the ZnO nanoribbons and nanoparticles show four traps, which have energies of 0.31 eV, 0.23 eV, 0.87 eV, and 0.44 eV and 0.27 eV, 0.22 eV, 0.88 eV, and 0.51 eV, respectively. From the DLTS spectrum of the nanoshuttles, we observe five traps with different activation energies of 0.13 eV, 0.28 eV, 0.25 eV, 0.94 eV, and 0.50 eV. The DLTS analysis revealed that the origin of the nanostructure defect energy levels can be attributed to Zinc vacancies (Vzn), Oxygen vacancies (Vo), Zinc interstitials (Zni), Oxygen interstitials (Oi), and Zinc antisites (Zno). Based on our analysis, the ZnO nanorods showed the lowest number of defect energy levels compared to the other ZnO morphologies. [ABSTRACT FROM AUTHOR]

Controlled growth of ZnO nanorods on various substrates is of great interest in photonic and electronic device applications. Also of interest is increasing the optical activity of zinc oxide nanorods in the visible spectrum. In this study, we report pH dependence for the morphology and photoluminescence of aligned ZnO nanorods grown on an indium tin oxide (ITO) coated glass substrate deposited by a wet chemical bath deposition method. The ZnO nanorods were grown by a chemical bath deposition technique using equimolar ratios of zinc (II) nitrate and hexamethylenetetramine in solution at 95 °C. The pH of the reaction solution prior to oven heating was varied from pH 5 to 10.6. Surface properties of the ZnO nanorods on ITO substrates were studied using scanning electron microscopy and photoluminescence spectroscopy. We also compared the use of NaOH to adjust the pH with the use of N[H.sub.4]OH, the latter necessary at higher pH due to the relative insolubility of zinc. It was found that the size of the nanorods can vary twofold with pH and the choice of base. Uniformity of coverage is also significantly dependent upon these variables and will be discussed as it relates to solubility and crystal growth. It was also found that the intensity of the photoluminescence in the visible range is pH dependent. For example, the intensity of luminescence at 550 nm for ZnO nanorods grown at pH 7 using N[H.sub.4]OH is 532% of the corresponding emission for a sample prepared at pH 5. PACS Nos.: 78.67.Qa, 78.67.-n, 78.55.Et. La croissance controlee de nanotiges de ZnO sur differents substrats est tres importante pour les applications en photonique et en dispositifs electroniques. Nous sommes egalement interesses par l'augmentation de l'activite optique des nanotiges d'oxyde de zinc dans le visible. Nous etudions ici la dependance sur le pH de la morphologie et de la photoluminescence de nanotiges alignees qui ont cru sur un substrat de verre recouvert d'une couche superficielle d'oxyde d'indium-etain (ITO), deposee par une methode de bain chimique humide. Les nanotiges de ZnO croissent par technique de depot en bain chimique utilisant un rapport equimolaire de nitrate de zinc et de hexamethylenetetramine en solution a 95 %. Nous varions, avant chauffage, le pH de la solution entre 5 et 10,6. La microscopie electronique a balayage et la spectroscopie de photoluminescence nous permettent d'analyser les proprietes de surface des nanotiges sur substrat de ITO. Nous comparons aussi l'ajustement du pH en utilisant du NaOH et du N[H.sub.4]OH, ce dernier etant necessaire a pH eleve, a cause de la solubilite relative du zinc. Nous trouvons que selon le pH et la base utilisee, la grosseur des nanotiges peut doubler. L'uniformite de couverture est egalement fonction de ces variables et nous en discutons, parce qu'elle est reliee a la solubilite et a la croissance du cristal. Nous trouvons que l'intensite de la photoluminescence dans le visible depend du pH de la solution. Par exemple, l'intensite de luminescence a 550 nm des nanotiges qui ont cru a pH 7 avec la base N[H.sub.4]OH, est 532 % de l'emission correspondante d'un echantillon fabrique a pH 5. [Traduit par la Redaction], 1. Introduction Zinc oxide is an important material with applications ranging from the fabrication of ultraviolet (UV) optical detectors to photovoltaic devices [1]. Among the various growth techniques developed, wet [...]

A high-speed, low-resistance inertial exercise trainer (IET, Impulse Training Systems, Newnan, Ga) is increasingly employed in rehabilitative and athletic performance settings. Repetitions on an IET are done through a large range of motion because multijoint movements occur over more than one plane of motion, with no limitation on velocities or accelerations attained. The current study purpose is to assess data reproducibility from an instrumented IET through multiple test-retest measures. Data collection methods required the IET left and right halves to be fitted with a TLL-2K force transducer (Transducer Techniques, Temecula, Calif) on one of its pulleys, and an infrared position sensor (Model CX3-AP-1A, automationdirect.com) located midway on the underside of each track. Signals passed through DI-158U signal conditioners (DATAQ Instruments, Akron, Ohio) and were measured with a four-channel analog data acquisition card at 4000 Hz. To assess data reproducibility, college-age subjects (n = 45) performed four IET workouts that were spaced 1 week apart. Workouts entailed two 60-second sets of repetitive knee-and hip-extensor muscle actions as subjects were instructed to exert maximal voluntary effort. Results from multiple test-retest measures show that the IET elicited reproducible intra- and interworkout data despite the unique challenge of multiplanar and multijoint exercise done over a large range of motion. We conclude that future studies in which IET performance measurement is required may choose to instrument the device with current methodology. Current practical applications include making IET data easier to comprehend for the coaches, athletes, and health care providers who use the device. KEY WORDS instrumentation, data reproducibility, force transducer

One dimensional zinc oxide (ZnO) nanostructures were fabricated using a low temperature chemical bath deposition technique. The ZnO nanorods were doped with cobalt using cobalt nitrate with cobalt concentration varying from 0% to 9%. The scanning electron microscope images of the nanostructures indicate that the diameter of ZnO nanorods increased with the increase in cobalt doping concentration. The optical characterizations of the doped and undoped samples were performed by investigating the variation in the band gap, the Urbach energy, the index of refraction, and the extinction coefficient with cobalt concentration. The dispersion of index of refraction in cobalt doped ZnO nanostructures was modeled based on the Wemple DiDomenico single oscillator model. The interband oscillator energy and the dispersion energy were estimated for different cobalt doped ZnO nanorod samples based on this model. [ABSTRACT FROM AUTHOR]

Different molar concentrations (0.05–0.2 M) of vanadium pentoxide nanoparticles were synthesized with and without polyvinylpyrrolidone (PVP) using hydrothermal method. The growth mechanism with different molar concentrations as well as the effect of PVP on the structural, optical, and electrical properties have been investigated. The size of the particles was measured from transmission electron microscopy (TEM) and x‐ray diffraction spectroscopy (XRD). Optical properties were analyzed through photoluminescence and absorption measurement. The electrical transport properties were analyzed by impedance spectroscopy and Van der Pauw method. From impedance measurements, dominance of grain boundary resistance over grain resistance was observed. The resistivity also decreased with increasing molar concentrations of nanoparticles with and without PVP. The highest temperature coefficient of resistance (TCR) value of −2.33 %/K with the lowest resistivity of 0.02 Ω. cm for V2O5 nanoparticle of 0.2 M concentration without using PVP was observed. Therefore, such V2O5 nanoparticles are a potential material for microbolometer applications. [ABSTRACT FROM AUTHOR]

Controlled growth of ZnO nanorods on various substrates is of great interest in photonic and electronic device applications. Also of interest is increasing the optical activity of zinc oxide nanorods in the visible spectrum. In this study, we report pH dependence for the morphology and photoluminescence of aligned ZnO nanorods grown on an indium tin oxide (ITO) coated glass substrate deposited by a wet chemical bath deposition method. The ZnO nanorods were grown by a chemical bath deposition technique using equimolar ratios of zinc (II) nitrate and hexamethylenetetramine in solution at 95 °C. The pH of the reaction solution prior to oven heating was varied from pH 5 to 10.6. Surface properties of the ZnO nanorods on ITO substrates were studied using scanning electron microscopy and photoluminescence spectroscopy. We also compared the use of NaOH to adjust the pH with the use of NH4OH, the latter necessary at higher pH due to the relative insolubility of zinc. It was found that the size of the nanorods can vary twofold with pH and the choice of base. Uniformity of coverage is also significantly dependent upon these variables and will be discussed as it relates to solubility and crystal growth. It was also found that the intensity of the photoluminescence in the visible range is pH dependent. For example, the intensity of luminescence at 550 nm for ZnO nanorods grown at pH 7 using NH4OH is 532% of the corresponding emission for a sample prepared at pH 5. [ABSTRACT FROM AUTHOR]

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Thermo-optical and structural properties of cobalt-doped zinc oxide (ZnO) nanorods grown by chemical bath deposition were investigated. The average nanorods diameter was found to increase with cobalt doping. X-ray diffraction (XRD), Raman, and Fourier Transform Infrared (FTIR) analysis confirm the substitution of cobalt into ZnO lattice without forming any impurities at higher doping and preserving the hexagonal wurtzite structure. Variations in the absorption spectrum, band gap, photoluminescence, electronic structure by X-ray photoelectron spectroscopy (XPS), and index of refraction were analyzed at different cobalt doping levels and annealing temperatures. The thermooptic coefficient of ZnO nanorods was extracted and explained regarding cobalt doping. We will also discuss the nature of cobalt incorporation in ZnO nanorods at various doping levels.