Chengshan Xue

Structural properties and photoluminescence of zinc nitride nanowires

Zinc nitride nanowires can be synthesized by nitridation reaction of zinc powder with ammonia gas in 500ml∕min at the nitridation temperature of 600 °C for 120 min. Studies by using x-ray diffraction indicate that zinc nitride nanowires are cubic in structure with the lattice constant a=0.9788nm. Observations by using scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy show that zinc nitride is of nanowire structure. Typical room temperature photoluminescence spectrum of zinc nitride nanowires exhibits an ultraviolet emission peak at 385 nm (3.22 eV) and a blue emission band centered at 450 nm (2.76 eV).

Fabrication of GaN nanowires by ammoniating Ga2O3/Al2O3 thin films deposited on Si(111) with radio frequency magnetron sputtering

GaN nanowires were synthesized by ammoniating Ga2O3/Al2O3 thin films deposited on Si(111) with radio frequency magnetron sputtering. The cylindrical structures were as long as several micrometres, with diameters ranging between?5 and 40?nm. X-ray diffraction (XRD, Rigaku D/max-rB Cu?K?), scanning electronic microscope (SEM, HitachiH-8010) and high-resolution TEM?(HRTEM) results show that most of the GaN nanowires have a single-crystal hexagonal wurtzite structure with major axis [001] alignment. A minority of them are polycrystalline, composed of micrograins with different growth orientations.

Growth of GaN nanowires by ammoniating Ga2O3 thin films deposited on quartz with radio frequency magnetron sputtering

GaN nanowires have been synthesized by ammoniating Ga2O3 oxide thin films. Ga2O3 films with a thickness of ~500 nm were deposited on quartz substrates by radio frequency magnetron sputtering. X-ray diffraction, scanning electronic microscope, transmission electronic microscope and high-resolution TEM results show that the majority of the GaN nanowires have a single-crystal hexagonal wurtzite structure with major axis [110] alignment. A minority are polycrystalline, composed of overlapped parallelepiped GaN nanocrystals, which gives the wires a herringbone topography. The diameters of the wires range from 10 to 90 nm and the lengths are up to 50 μm. The achievement of GaN nanowires by ammoniating Ga2O3 presents a novel method for synthesizing one-dimensional nanometre materials without the assistance of a template or a catalyst.

Synthesis of Large-scale GaN Nanowires by Ammoniating Ga2O3/V Films

Abstract Large-scale GaN nanowires were synthesized on Si(111) substrates through ammoniating Ga2O3/V films. The as-grown products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results reveal that the grown GaN nanowires have a smooth and clean surface with diameters ranging from 20 nm to 60 nm and lengths of about several tens of micrometers. The results of HRTEM and selected-area electron diffraction (SAED) show that the nanowires are pure hexagonal GaN single crystal. The photoluminescence (PL) spectrum indicates that the GaN nanowires have good emission property. The growth mechanism is discussed briefly.

Synthesis and Characterization of Glomerate GaN Nanowires

Glomerate GaN nanowires were synthesized on Si(111) substrates by annealing sputtered Ga2O3/Co films under flowing ammonia at temperature of 950 °C. X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy and Fourier transformed infrared spectra were used to characterize the morphology, crystallinity and microstructure of the as-synthesized samples. Our results show that the samples are of hexagonal wurtzite structure. For the majority of GaN nanowires, the length is up to tens of microns and the diameter is in the range of 50–200 nm. The growth process of the GaN nanowires is dominated by Co–Ga–N alloy mechanism.

FORMATION OF GaN FILM BY AMMONIATING Ga2O3 DEPOSITED ON Si SUBSTRATE WITH ELECTROPHORESIS

The gallium nitride (GaN) films have been successfully fabricated on silicon (111) substrates through ammoniating Ga2O3 films deposited by electrophoresis. The structure and composition of the formed films were characterized by Fourier transform infrared (FTIR) transmission spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results indicate that the films formed in this study are polycrystalline GaN with hexagonal wurtzite structure.

Preparation and properties of GaN nanostructures by post-nitridation technique

Abstract Nanostructure GaN films were prepared by post-nitridation technique. The morphology and structure of GaN nanowires are investigated by using transmission electron microscopy and scanning electron microscopy. The growth mechanism of the GaN nanowires is unlikely to be controlled by the well-known vapor–liquid–solid mechanism, vapor–solid phase was involved in the growth of GaN nanostructures. A strong blue photoluminescence is observed for room temperature measurement.

Synthesis of GaN nanowires by CVD method: effect of reaction temperature

GaN nanowires are fabricated on Si substrates by ammoniating Ga2O3/NiCl2 thin films using chemical vapour deposition method. The influence of reaction temperature on microstructure, morphology and optical properties of GaN nanowires is characterised by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectrophotometer, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and photoluminescence. The results demonstrate that the GaN nanowires are single crystalline and exhibit hexagonal wurtzite symmetry. The best crystalline quality was achieved for an reaction temperature of 1150°C for 15 min. The growth process follows vapour–liquid–solid mechanism and Ni plays an important role as the nucleation point and as a catalyst.

Influence of Mg Doping on GaN Nanowires

Magnesium-doped GaN nanowires with different dopant concentrations are synthesized by ammoniating Ga(2)O(3) thin films doped with Mg at 900 degrees C. Scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HRTEM), and room-temperature photoluminescence (PL) are employed to characterize the influences on the morphology, structure, crystallinity, and optical properties of Mg-doped GaN nanowires. The results demonstrate that the nanowires are single-crystalline with hexagonal wurzite structure. GaN nanowires doped with 5 atom % of Mg have the best morphology and crystallinity with a single-crystalline structure, and at this composition the PL spectrum with the strongest UV peak is observed. The growth mechanism of crystalline GaN nanowires is discussed briefly.

Structure and luminescence of GaN films by sputtering post-annealing-reaction technique

Abstract Gallium nitride (GaN) films were prepared on quartz substrates by sputtering post-annealing-reaction technique. The sputtered Ga 2 O 3 films were used as a precursor for GaN growth. X-ray diffractometer, X-ray photoelectron spectroscopy and TEM measurement results indicate that the obtained GaN films are polycrystalline films with hexagonal structure, which consist of single-crystalline nanorods. A strong blue photoluminescence located at 458 nm and a UV photoluminescence located at 370 nm is observed at room temperature.