Search

A new method using defect-pit-assisted growth technology to successfully synthesize the high-quality single crystalline GaN nanostructures by ammoniating Ga2O3 films was proposed in this paper. During the ammoniating process, the amorphous middle buffer layer may unavoidably produce some defects and dislocations. Some defect pits come out, which have the lowest surface energy and can subsequently be used as a mask/template or act as potential nucleation sites to fabricate the GaN actinomorphic nanostructures. The as-prepared products are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The results indicate that all the reflections of the samples can be indexed to the hexagonal GaN phase and the clear lattice fringes in HRTEM further confirm the growth of high-quality single-crystal GaN nanostructures. The SEM images show that the nanostructures have been realized under different experimental conditions exhibiting different shapes: nanowires, nanorods, and nanobelts. No particles or other nanostructures are found in the SEM study, demonstrating that the product possesses pure nanostructures. These nanostructures show a very good emission peak at 366 nm, which will have a good advantage for applications in laser devices using one-dimensional structures. Finally, the growth mechanism is also briefly discussed. [ABSTRACT FROM AUTHOR]

GaN nanowires were successfully synthesized on Si(111) substrates by ammoniating the Ga2O3/ZnO films at 900??C. The structure, morphology and optical property of the as-prepared GaN nanowires were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission transmission electron microscope (FETEM), Fourier transform infrared spectrum (FTIR) and fluorescence spectrophotometer. The results show that the GaN nanowires have a hexagonal wurtzite structure with lengths of about several micrometers and diameters ranging from 30?nm to 120?nm. The representative photoluminescence spectrum at room temperature exhibited a strong emission peak at 374.1?nm and two weak emission peaks at 437.4?nm and 473.3?nm. Finally, the growth mechanism is also briefly discussed. [ABSTRACT FROM AUTHOR]

ZnO thin films were prepared on Si(111) substrates by pulsed laser deposition (PLD). Then, the samples were annealed at different temperatures in NH3 ambient and their properties were investigated particularly as a function of annealing temperature. The structure, morphology, and optical properties of ZnO films were studied by x-ray diffraction (XRD), Fourier transform infrared spectroscope (FTIR), scanning electron microscope (SEM), and photoluminescence (PL). The results show that the increase of annealing temperature makes for the improvement in the crystal quality and surface morphology below the temperature of 650°C. However, when the annealing temperature is above 650°C, the ZnO films will volatilize and, especially at 750°C, ZnO will volatilize completely. [ABSTRACT FROM AUTHOR]

Single crystalline wurzite GaN nanorods are successfully synthesized on the tantalum catalyzed Si substrate by RF magnetron sputtering. The products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), transmission electron microscopy (TEM), selected-area electron diffraction (SAED) and photoluminescence (PL). The results show that the nanorods have a hexagonal wurtzite structure with diameters ranging from 80 to 200?nm and lengths typically up to 10??m. The PL spectrum exhibits a strong UV light emission at 364?nm. The growth mechanism of the crystalline GaN nanorods is discussed briefly. [ABSTRACT FROM AUTHOR]

GaN nanorods have been successfully synthesized on Si(111) substrates by magnetron sputtering through ammoniating the Ga2O3/ZnO films at 950??C in a quartz tube. The GaN nanorods have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission transmission electron microscope (FETEM), Fourier transform infrared (FTIR) system and fluorescence spectrophotometer. The results show that the nanorods are pure hexagonal GaN wurtzite structure with lengths of about several micrometers and diameters ranging from 100?nm to 750?nm, and the growth direction of GaN nanorods is perpendicular to (101) plane. The photoluminescence (PL) spectrum indicates that the good emission property for the nanorods. Finally, the growth mechanism is also briefly discussed. [ABSTRACT FROM AUTHOR]

Two types of novel bicrystalline ZnO nanowires have been synthesized by a thermal evaporation method. The morphology and microstructure of the nanowires have been extensively investigated. One type of the nanowires has agg twin boundary extending down its entire length with twinning plane and the zone axis. The other type is those nanowires with twin crystal-single crystal junction. The twin defects in the Sn-Zn alloy droplets in the initial growth process are proposed for interpreting the growth of these two kinds of bicrystalline nanowires. [ABSTRACT FROM AUTHOR]