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Large areas of ZnO horseshoe-shaped nanorods have been fabricated vertically on MgO-coated Si (1 1 1) substrates by chemical vapor deposition method. The well-aligned nanorod arrays were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscope (HRTEM), energy-dispersive X-ray spectroscopy (EDS), and photoluminescence spectroscopy (PL). The results show that the nanorods are perfect single crystals with hexagonal wurzite structure along the [0 0 0 1] growth direction. The nanorods have regular horseshoe shape, and the diameter of the rods rang 70–99 nm while the length is about 600 nm. The PL spectrum exhibits a strong peak at 500.8 nm and two relatively weak emission bands centered at 387.7 nm and 648.6 nm, which indicates that the ZnO arrays are of excellent optical quality.

ZnO hexagonal prisms have grown on MgO-coated Si (111) substrates by chemical vapor deposition. The process has two steps : the preparation of MgO-coated Si (111) substrates and the preparation of uniform ZnO hexagonal prisms. Some nucleation sites are provided on the Si substrates by the MgO layers, which have the capability to improve the growth of ZnO prisms in the heteroepitaxy. The prisms are single crystals with a preferential growth along the c axis and they are well-faceted at both the end and side surfaces. Room-temperature photoluminescence measurement of these ZnO prisms have shown a strong ultraviolet (UV) emission band centered at 393 nm and a weak green emission band centered at 507 nm, which may be provide an improvement in novel ultraviolet light-emitting devices. In addition, a possible mechanism for the prism growth is proposed based on the analysis by electron microscopy.

Gallium nitride ( GaN ): nanostructured materials are synthesized by ammoniating Ga2O3/Nb films which are deposited in turn on Si(111) substrates at 900°C. The morphology and structure of the nanostructured materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Optical property of GaN nanostructured materials are analyzed by photoluminescence (PL). The results demonstrated that as-synthesized nanostructured materials are hexagonal wurtzite-structured. Ammoniating time of the samples has an evident influence on the morphology of GaN nanostructured materials synthesized by this method. The PL spectra indicate good emission property for the nanostructured materials. Finally, the growth mechanism is also briefly discussed.

Novel ZnO tetrapods have been successfully synthesized on MgO-coated Si (111) substrates by chemical vapor deposition method (CVD) at 1000 °C. The tetrapod is made up of four legs and added prisms. The particles are single crystal with the wurtzite hexagonal structure, and the growth direction of the tetrapods changes from [0001] to [01 1 ¯ 1]. This configuration is a new member in the family of ZnO microstructures. The pre-prepared MgO films on the Si (111) substrates can promote the growth of the tetrapods effectively. In addition, the octahedral multiple twin model and polar surfaces are proposed for interpreting the growth of the tetrapods.

Three types of novel ZnO hexagonal microprisms have been grown on MgO-coated Si (111) substrates via carbon-thermal evaporation. In this work, the pre-prepared MgO films on the substrates can solve a troublesome lattice mismatch problem in the heteroepitaxy, which has the capability for promoting the formation of the ZnO nuclei. The structural analyses confirm that the structures are perfect single crystals with hexagonal wurtzite structure along the [0001] growth direction. The diameter of the prisms ranges from 0.6 to 2.5 μm and the length is about 3 μm. PL spectra of the ZnO products exhibit a UV emission peak at 388 nm and a broad green emission peak at 514 nm. In addition, the growth mechanism of the crystalline ZnO prisms is discussed briefly, emphasizing the effect of polar orientation on the nucleation.

A novel method was utilized to synthesize one-dimensional β-Ga 2 O 3 nanostructures. In this method, β-Ga 2 O 3 nanostructures have been successfully synthesized on Si(111) substrates through annealing sputtered Ga 2 O 3 /Mo films under flowing ammonia in a quartz tube. The as-obtained samples were analyzed in detail using the methods of X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDX) attached to the HRTEM instrument. The results show that the formed nanostructures are single-crystalline Ga 2 O 3 . The annealing temperature has an evident influence on the morphology of the β-Ga 2 O 3 nanostructures. The growth mechanism of the β-Ga 2 O 3 nanostructures is also discussed by conventional vapor–solid (VS) mechanism.

Zinc oxide columns have been grown on an MgO-coated silicon (111) substrate by the carbon-thermal evaporation method at 1050 °C. The MgO layer obtained from the substrate pre-dripped in Mg(NO3)2 solution by the use of a dropper can solve the troublesome lattice mismatch problem in the heteroepitaxy and promote the growth of ZnO columns effectively. The as-prepared ZnO structures were characterized by using X-ray diffraction (XRD), field-emission transmission electron microscope (FETEM), selection area electron diffraction (SAED), and photoluminescence (PL) spectrum. The results show that the columns are highly crystalline with the wurtzite hexagonal structure, and grow along the [0001] in the c-axis direction. Photoluminescence (PL) spectra of the as-synthesized microstructures exhibit broad green emission peaks at ∼514 nm. In addition, the growth mechanism of the two ZnO structures is discussed based on the analysis briefly based on the time-dependent experiment.

Two types of novel Mg-doped pencil-shaped ZnO microprisms had been successfully synthesized on Mg(NO3)2-coated Si (1 1 1) substrates by thermal chemical vapor deposition method. The as-prepared ZnO prisms were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission transmission electron microscope (FETEM), selected area electron diffraction (SAED), and photoluminescence (PL) spectroscopy. The straight microprisms are made up of hexagonal pyramids tips and hexagonal prisms bodies. Both of the structures are perfect single crystal and have grown along the [0 0 0 1] direction preferentially. Photoluminescence reveals a red-shift at around 387 nm which is induced by Mg doping and a green light emission peak at around 511 nm. The pencil-shaped ZnO microstructure can provide an improvement in novel ultraviolet light-emitting devices. In addition, the growth mechanism of the special ZnO microprisms is discussed briefly.

Polar surface dominated ZnO brush-like nanostructures have been successfully synthesized on Si substrates via a carbon-thermal reduction method at a temperature of 900 °C. Specially, the axis of the as-prepared brush-like nanostructures is a straight nanorod along the [0 0 0 1] direction and enclosed by six { 0 1 1 ¯ 0 } surfaces, which grew first; the sixfold symmetric nanonails were later formed along the equivalent a axes ( 0 1 1 ¯ 0 > ) perpendicular to the central nanorod, and the brush is formed by epitaxial growth of nanonails on the central nanorod. The growth of the structures is based on firstly sprouting of nanorods and then epitaxial growth of nanonails in the six symmetric [ 0 1 1 ¯ 0 ] directions. Based on the testing results, the growth mechanism of the ZnO brush-like nanostructures was discussed, emphasizing the self-catalysed of ZnO and the polar orientation of ZnO nanostructures, and the formation of the nanonails may due to the different chances of absorbing the arriving vapors.

Well-crystallized ZnO nanowires have been successfully synthesized on NiCl2-coated Si substrates via a carbon thermal reduction deposition process. The pre-deposited Ni nanoparticles by dipping the substrates into NiCl2 solution can promote the formation of ZnO nuclei. The as-synthesized nanowires were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectrum. The results demonstrate that the as-fabricated nanowires with about 60 nm in diameter and several tens of micrometers in length are preferentially arranged along [0001] direction with (0002) as the dominate surface. Room temperature PL spectrum illustrates that the ZnO nanowires exist a UV emission peak and a green emission peak, and the peak centers locate at 387 and 510 nm. Finally, the growth mechanism of the nanowires is briefly discussed.

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.

GaN nanowires doped with Mg have been synthesized at different temperature through ammoniating the magnetron-sputtered Ga2O3/Au layered films deposited on Si substrates. X-ray diffraction (XRD), Scanning electron microscope (SEM), high-resolution TEM (HRTEM) equipped with an energy-dispersive X-ray (EDX) spectrometer and photoluminescence (PL) were used to analyze the structure, morphology, composition and optical properties of the as-synthesized sample. The results show that the ammoniating temperature has a great impact on the properties of GaN. The optimally ammoniating temperature of Ga2O3/Au layer is 900 ∘C for the growth of GaN nanowires(NWs). The band gap emission (358 nm) relative to that (370 nm) of undoped GaN NWs has an apparent blueshift, which can be ascribed to the doping of Mg. Finally, the growth mechanism is also briefly discussed.

In this work, GaN nanowires were fabricated on Si substrates coated with NiCl2 thin films using chemical vapor deposition (CVD) method by evaporating Ga2O3 powder at 1100 °C in ammonia gas flow. X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscope (HRTEM) and photoluminescence (PL) spectrum are used to characterize the samples. The results demonstrate that the nanowires are single-crystal GaN with hexagonal wurtzite structure. The growth mechanism of GaN nanowires is also discussed.

GaN nanowires doped with Mg have been synthesized on Si (111) substrate through ammoniating Ga 2 O 3 films doped with Mg under flowing ammonia atmosphere. The Mg-doped GaN nanowires were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM) and photoluminescence (PL). The results demonstrate that the nanowires were single crystalline with hexagonal wurzite structure. The diameters of the nanowires ranged 20–30 nm and the lengths were about hundreds of micrometers. The intense PL peak at 359 nm showed a blueshift from the bulk band gap emission, attributed to Burstein–Moss effect. The growth mechanism of the crystalline GaN nanowires is discussed briefly.

ZnO nanoporous belts with a smooth surface and high pore density have been successfully synthesized; the simple growth method is applicable to produce high-yield single-crystalline ZnO nanoporous belts with a relatively high purity and at a low cost. The morphology and microstructure and optical properties of ZnO nanoporous belts were analyzed by X-ray diffraction (XRD), Fourier transform infrared system (FTIR), scanning electron microscope (SEM), field-emission transmission electron microscope (FETEM), selective area electron diffraction (SAED), and photoluminescence (PL) spectroscopy. Results reveal that ZnO nanoporous belts possess good crystalline quality. The formation mechanism of the special ZnO microstructure is discussed, emphasizing the effect of polar orientation on the nucleation and growth of ZnO nanoporous belts.

Magnesium-doped GaN nanowires with different dopant concentrations are synthesized and their morphology, structure, growth properties, crystallinity, and optical properties investigated. The nanowires are single-crystalline with hexagonal wurzite structure, and doping with 5 atom % of Mg gives nanowires with the best morphology and crystallinity (see HRTEM image). Magnesium-doped GaN nanowires with different dopant concentrations are synthesized by ammoniating Ga2O3 thin films doped with Mg at 900 °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.

Novel W-shaped porous ZnO nanobelt with the periodical junction angles of about 118° and straight porous ZnO nanobelt have been successfully synthesized. The W-shaped structure growth changes from [0 0 0 1] to [ 0 1 1 ¯ 1 ] periodically. The straight nanobelt grows along [0 0 0 1] direction. Both of the structures have smooth surfaces with high porous density. Based on our X-ray diffraction (XRD), electron microscopy and photoluminescence (PL) spectrum study, the growth mechanism of the special ZnO nanostructures is discussed, emphasizing the effect of alteration of the reactant concentration for two different morphologies.

ZnO films are firstly prepared on Si substrates by pulsed laser deposition (PLD) technique and then the Ga 2 O 3 films are deposited on ZnO/Si substrates by magnetron sputtering system. The low-dimensional GaN nanostructured materials are obtained by ammoniating the Ga 2 O 3 /ZnO films from 850 to 1000 °C for 15 min in a quartz tube. X-ray diffraction (XRD), scanning electron microscope (SEM), field-emission transmission electron microscope (FETEM), Fourier transform infrared spectrophotometer (FTIR) and photoluminescence (PL) are used to analyze the structure, morphology and optical properties of as-grown samples. The results show that their properties are investigated particularly as a function of ammoniating temperatures. Large quantities of high-quality GaN nanowires are successfully fabricated at 900 °C with lengths of about tens of micrometers and diameters ranging from 30 to 120 nm, which could supply an attractive potential to harmonically incorporate future GaN optoelectronic devices into Si-based large-scale integrated circuits. Finally, the growth mechanism is also briefly discussed.

A novel lanthanon seed was employed as the catalyst for the growth of GaN nanorods. Large-scale GaN nanorods were synthesized successfully through ammoniating Ga2O3/Tb films sputtered on Si(1 1 1) substrates. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and photoluminescence spectrum were used to characterize the samples. The results demonstrate that the nanorods are single-crystal GaN with hexagonal wurtzite structure and possess good optical properties. The growth mechanism of GaN nanorods is also discussed.

β-Ga2O3nanostructured materials have been obtained on Si(111) substrates by annealing the Ga2O3/V films at different temperatures. X-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM) and photoluminescence (PL) spectrum were used to analyze the structure, morphology and optical properties of β-Ga2O3 nanostructured films. These properties were investigated particularly as a function of annealing temperature. Our results indicate that the β-Ga2O3 nanorods annealed at 950 ∘C have the best morphology and crystallinity. These nanorods are pure monoclinic Ga2O3 structures with lengths of about 5 μm and diameters of about 180 nm, which is conducive to the application of nanodevices. Finally, the growth mechanism is also discussed briefly.

A novel rare earth metal seed Tb was employed as the catalyst to grow GaN nanorods. Large-scale GaN nanorods were synthesized successfully through ammoniating Ga 2 O 3 /Tb films sputtered on Si(1 1 1) substrates. Studies by X-ray diffraction indicate that the nanorods are hexagonal GaN. Observations by scanning electron microscopy and high-resolution transmission electron microscopy show that GaN is of single-crystal nanorod structure. Photoluminescence spectrum shows the products possess good luminescent properties. The growth mechanism of GaN nanorods is also discussed.

A novel rare earth metal seed was employed as the catalyst for the growth of GaN nanorods. Large-scale GaN nanorods were synthesized successfully through ammoniating Ga 2 O 3 /Tb films sputtered on Si(1 1 1) substrates. Scanning electron microscopy, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy were used to characterize the structure, morphology, and composition of the samples. The results demonstrate that the nanorods are high-quality single-crystal GaN with hexagonal wurtzite structure. The growth mechanism of GaN nanorods is also discussed.

ZnO thin films with different thickness (the sputtering time of ZnO buffer layers was 10 min, 15 min, 20 min, and 25 min, respectively) were first prepared on Si substrates using radio frequency magnetron sputtering system and then the samples were annealed at 900 °C in oxygen ambient. Subsequently, a GaN epilayer about 500 nm thick was deposited on ZnO buffer layer. The GaN/ZnO films were annealed in NH 3 ambient at 950 °C. X-ray diffraction (XRD), atom force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to analyze the structure, morphology, composition and optical properties of GaN films. The results show that their properties are investigated particularly as a function of the sputtering time of ZnO layers. For the better growth of GaN films, the optimal sputtering time is 15 min.

ZnO thin films were first prepared on Si(111) substrates using a radio frequency magnetron sputtering system. Then the as-grown ZnO films were annealed in oxygen ambient at temperatures of 700, 800, 900, and 1000°C , respectively. The morphologies of ZnO films were studied by an atom force microscope (AFM). Subsequently, GaN epilayers about 500 nm thick were deposited on the ZnO buffer layers. The GaN/ZnO films were annealed in NH3 ambient at 900°C. The microstructure, morphology and optical properties of GaN films were studied by x-ray diffraction (XRD), AFM, scanning electron microscopy (SEM) and photoluminescence (PL). The results are shown, their properties having been investigated particularly as a function of the ZnO layers. For better growth of the GaN films, the optimal annealing temperature of the ZnO buffer layers was 900°C.

Single-crystalline wurtzite GaN nanowires have been synthesized through ammoniating Ga2O3/Ta films by RF magnetron sputtering. The products have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), X-ray photoelectron microscopy (XPS) and photoluminescence (PL). The results show that the nanowires have a hexagonal wurtzite structure with diameters ranging from 10 nm to 30 nm and lengths typically up to several tens of micrometers. The representative photoluminescence spectrum at room temperature exhibits a strong UV light emission band centered at 364 nm. The growth mechanism of the crystalline GaN nanowires is discussed briefly.

A novel method is applied to prepare nanorods. In this method, nanorods have been successfully synthesized on Si(111) substrates through annealing sputtered Ga 2 O 3 /Nb films under flowing ammonia at 950 °C in a quartz tube. The as-synthesized nanorods are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectra. The results show that the nanorod is single-crystalline GaN. It has a diameter of about 200 nm and lengths typically up to several micrometers. Photoluminescence spectrum under excitation at 325 nm only exhibits a UV light emission peak is located at about 368.5 nm. Finally, the growth mechanism of nanorods is also briefly discussed.

A new method using two-step growth technology to successfully synthesize high-quality single crystalline GaN nanobelts was employed in this paper. This growth method is applicable to continuous syn...

Rare earth metal seed Tb was employed as catalyst for the growth of GaN wires. GaN nanowires were synthesized successfully through ammoniating Ga 2 O 3 /Tb films sputtered on Si(1 1 1) substrates. The samples characterization by X-ray diffraction and Fourier transform infrared indicated that the nanowires are constituted of hexagonal wurtzite GaN. Scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy showed that the samples are single-crystal GaN nanowire structures. The growth mechanism of the GaN nanowires is discussed.

GaN nanowires and nanorods have been successfully synthesized on Si(1 1 1) substrates by magnetron sputtering through ammoniating Ga 2 O 3 /V films at 900 °C in a quartz tube. X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectrum were carried out to characterize the structure, morphology, and photoluminescence properties of GaN sample. The results show that the GaN nanowires and nanorods with pure hexagonal wurtzite structure have good emission properties. The growth direction of nanostructures is perpendicular to the fringes of (1 0 1) plane. The growth mechanism is also briefly discussed.

Wurtzite GaN nanorods have been successfully synthesized on Si(111) substrates through ammoniating Ga 2 O 3 /Nb films under flowing ammonia atmosphere at 950 ∘ C in a quartz tube. The nanorods have been confirmed as hexagonal wurtzite GaN by X-ray diffraction (XRD) and selected-area electron diffraction (SAED). Scanning electron microscopy (SEM) and field-emission transmission electron microscope (FETEM) reveal that the nanorods are straight and uniform, with a diameter of ranging from 100 to 200 nm and lengths up to several microns. The photoluminescence spectra (PL) measured at room temperature only exhibit a strong emission peak at 368.5 nm. Finally, the growth mechanism of GaN nanorods is also briefly discussed.

Pine-needle-shaped GaN nanorods have been successfully synthesized on Si(111) substrates by ammoniating Ga 2 O 3 /Nb films at 950 ∘ C in a quartz tube. The products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and field-emission transmission electron microscope (FETEM). The results show that the pine-needle-shaped nanorods have a pure hexagonal GaN wurtzite with a diameter ranging from 100 to 200 nm and a length up to several microns. The photoluminescence spectra (PL) measured at room temperature only exhibit a strong emission peak at 368 nm. Finally, the growth mechanism of GaN nanorods is also briefly explored.

A novel method was applied to prepare β-Ga2O3 nanorods. In this method, β-Ga2O3 nanorods have been successfully synthesized on Si(1 1 1) substrates through annealing sputtered Ga2O3/Mo films under flowing ammonia at 950 °C in a quartz tube. The as-synthesized nanorods are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR). The results show that the nanorod is single-crystalline Ga2O3 with monoclinic structure. The β-Ga2O3 nanorods are straight and smooth with diameters in the range of 200–300 nm and lengths typically up to several micrometers. The growth process of the β-Ga2O3 nanorods is probably dominated by conventional vapor–solid (VS) mechanism.

Large quantities of GaN nanorods have been successfully synthesized on Si(1 1 1) substrates by magnetron sputtering through ammoniating the Ga 2 O 3 /ZnO films at 950 °C in a quartz tube. The GaN nanorods are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), a field-emission transmission electron microscope (FETEM), a Fourier transform infrared (FTIR) spectrophotometer and a fluorescence spectrophotometer. The results show that the nanorods have pure hexagonal GaN wurtzite structure, with lengths of about several micrometers and diameters of about 200 nm. The clear lattice fringes demonstrate that the synthesized nanorods are single-crystal GaN. The FTIR spectrum further confirms that the GaN is obtained under this condition. The representative photoluminescence spectrum at room temperature exhibited a strong emission peak at 375.7 nm and two weak emission peaks at 436.2 and 475.5 nm. The GaN nanorods show a very good emission property, which will have a good advantage for applications in laser device using one-dimensional structures. Finally, the growth mechanism is also briefly discussed.

InN film was synthesized by ammoniating indium film on Si(1 1 1) substrates. The samples were analyzed by X-ray diffraction (XRD), X-ray photo-electron spectroscopy (XPS), atomic force microscopy (AFM) and transmission electron microscopy (TEM). The XRD and TEM show that nanoparticles were hexagonal InN single crystals.

Single-crystalline GaN nanowires and nanorods have been successfully grown on Si(1 1 1) substrates by magnetron sputtering through ammoniating the Ga 2 O 3 /Nb films at 900 °C in a quartz tube. The GaN nanowires and nanorods have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission transmission electron microscope (FETEM), and photoluminescence. The results show that the diameters of the nanowires are about 50 nm while the diameters of the nanorods are within 100–200 nm. Photoluminescence of the GaN nanostructure materials revealed only a strong and broad UV light emission peak at 369 nm. Finally, the growth mechanism of GaN nanostructure materials is also briefly discussed.

Single-crystalline GaN nanorods were successfully synthesized on Si(1 1 1) substrates through ammoniating Ga 2 O 3 /Mo films deposited on the Si(1 1 1) substrate by radio frequency magnetron sputtering technique. The as-synthesized nanorods are confirmed as single-crystalline GaN with wurtzite structure by X-ray diffraction (XRD), selected-area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). Scanning electron microscopy (SEM) displays that the GaN nanorods are straight and smooth with diameters in the range of 100–200 nm and lengths typically up to several micrometers. X-ray photoelectron spectroscopy (XPS) confirms the formation of bonding between Ga and N. The representative photoluminescence spectrum at room temperature exhibits a strong and broad emission band centered at 371.1 nm, attributed to GaN band-edge emission. The growth process of GaN nanorod may be dominated by vapor–solid (VS) mechanism.

Needle-shaped GaN nanowires have been synthesized on Si (111) substrate through ammoniating Ga2O3/MgO films under flowing ammonia atmosphere at the temperature of 950 °C. The as-synthesized GaN nanowires were characterized by X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, scanning electron microscope (SEM) and high-resolution transmission electron microscopy (HRTEM). The results demonstrate that these nanowires are hexagonal GaN and possess a smooth surface with an average diameter about 200 nm and a length ranging from 5 μm to 15 μm. In addition, the diameters of these nanowires diminish gradually. The growth mechanism of crystalline GaN nanowires is discussed briefly.

GaN nanowires were successfully synthesized on Si(111) substrates by ammoniating the Ga 2 O 3 /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.

GaN nanowires were synthesized by ammoniating Ga2O3 films on Ti layers deposited on Si (111) substrates at 950 °C. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR) and high-resolution transmission electron microscopy (HRTEM). The XRD, FTIR and HRTEM studies showed that these nanowires were hexagonal GaN single crystals. SEM observation demonstrated that these GaN nanorods with diameters ranging from 50 nm to 100 nm and lengths up to several micrometers intervene with each other on the substrate.

As-grown ZnO thin films are annealed in O 2 ambient for 15 min at the temperature of 700 °C, 800 °C, 900 °C and 1000 °C, respectively. Then the Ga 2 O 3 thin films are deposited on ZnO/Si(111) substrates by sputtering Ga 2 O 3 target in a JCK-500A radio frequency magnetron sputtering system. The low dimensional GaN nanostructured materials are obtained on Si substrates by ammoniating the Ga 2 O 3 /ZnO films at 950 °C for 15 min in a quartz tube. X-ray diffraction (XRD), Scanning electron microscope (SEM), Fourier transform infrared spectrophotometer (FTIR) and photoluminescence (PL) are used to analyze the structure, morphology and optical properties of GaN nanostructured films. The results show that their properties are investigated particularly as a function of annealing temperature of ZnO layer. The mechanism is also briefly discussed.

ZnO buffer layers were used in the fabrication of GaN films by pulsed laser deposition (PLD) in order to improve the initial nucleation and growth of GaN films when they are annealed in ammonia ambience at different temperatures. The crystalline quality, composition and surface morphology of the films were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) analysis and atomic force microscopy (AFM). Through the analyses of measured results, a conclusion can be drawn that the crystalline quality of GaN films deposited on ZnO buffer layers is much higher than that of those deposited directly on Si substrates with the volatilization of ZnO. The volatilization of ZnO buffer layers gives the grains of GaN more chances to move and form Ga–N bonds at high temperatures. The annealing temperature markedly affects the preparation of GaN films and the optimum annealing temperature is 950 °C under our experimental conditions.