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1.
Morphologies of GaN one-dimensional materials 总被引:8,自引:0,他引:8
J.Y. Li Z.Y. Qiao X.L. Chen Y.G. Cao Y.C. Lan C.Y. Wang 《Applied Physics A: Materials Science & Processing》2000,71(5):587-588
GaN one-dimensional materials with different morphologies were formed on LaAlO3 crystal, silicon crystal and quartz glass substrates through a simple sublimation method. They were characterized by powder
X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray (EDX) spectroscopy.
FE-SEM images showed that the morphologies of the one-dimensional materials included straight nanorods, curved nanowires,
nanoribbons, zigzag nanorods and beaded or capture-tree nanorods. XRD and EDX studies indicated that all the one-dimensional
materials were wurtzite GaN.
Received: 14 July 2000 / Accepted: 17 July 2000 / Published online: 20 September 2000 相似文献
2.
J.Y. Li X.L. Chen Z.Y. Qiao Y.G. Cao M. He T. Xu 《Applied Physics A: Materials Science & Processing》2000,71(3):349-350
Self-aligned GaN nanowire quasi-arrays were synthesized on MgO crystal through a simple gas reaction method. They were characterized
by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy
and high-resolution transmission electron microscopy (HRTEM). FE-SEMimages showed that the product consisted of quasi-arrays
of nanowires. XRD, EDX and HRTEM indicated that the nanowires were wurtzite GaN single crystals.
Received: 19 June 2000 / Accepted: 21 June 2000 / Published online: 9 August 2000 相似文献
3.
Highly oriented GaN nanowire arrays have been achieved by the catalytic reaction of gallium with ammonium. The resulting materials
were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), energy dispersive X-ray
spectroscopy (EDS), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). SEM images show
that the resulting materials are nanowire arrays with a uniform length of about 10 μm. XRD, EDS, TEM and SAED indicate that
the nanowire arrays are single-crystal hexagonal GaN with a wurtzite structure. They have diameters of 10 to 20 nm.
Received: 2 October 2002 / Accepted: 7 October 2002 / Published online: 17 December 2002
RID="*"
ID="*"Corresponding author. E-mail: wwwangjc@sina.com 相似文献
4.
In this paper, we report on the characteristics of GaN films grown on Si(111) at a low temperature (200 °C) by electron cyclotron resonance (ECR) plasma-assisted metalorganic chemical vapor deposition (PA-MOCVD). Structural analysis of the GaN films was performed by using scanning electron microscopy (SEM), atomic force miscroscopy (AFM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), and Rutherford backscattering spectrometry (RBS). Post deposition analysis revealed high quality crystalline GaN was obtained at this low temperature. Electrical analysis of the GaN films was done by using current-voltage (I-V) measurements where electrical characterizations were carried on GaN/Si heterojunction and Schottky barrier diodes. Rectification behaviour was observed for the isotype GaN/Si (n-n) heterojunction. Ideality factors and Schottky barrier heights for Ni and Cr Schottky barriers on GaN, were deduced to be 1.4 and 1.7; and 0.62 and 0.64 eV, respectively. 相似文献
5.
Fabrication of bamboo-shaped GaN nanorods 总被引:1,自引:0,他引:1
H. Li J.Y. Li M. He X.L. Chen Z. Zhang 《Applied Physics A: Materials Science & Processing》2002,74(4):561-562
Bamboo-shaped GaN nanorods were formed through a simple sublimation method. They were characterized by means of X-ray powder
diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected-area
electron diffraction (SAED). The TEM image showed that the nanorods were bamboo-like. XRD, HRTEM and SAED patterns indicated
that the nanorods were single-crystal wurtzite GaN.
Received: 8 January 2001 / Accepted: 28 April 2001 / Published online: 20 December 2001 相似文献
6.
Single crystalline GaN nanoribbons were synthesized through nitriding Ga2O3 thin films deposited on sapphire (0001) substrates by radio frequency magnetron sputtering. The component and structure of nanoribbons were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The flat and smooth ribbon-like nanostructures are high quality single crystalline hexagonal wurtzite GaN. The thickness and width-to-thickness ratio of the grown GaN nanoribbons are in the range of 8-15 nm and ∼5-10, respectively. 相似文献
7.
High-quality GaN nanowires synthesized using a CVD approach 总被引:3,自引:0,他引:3
High-quality GaN nanowires were synthesized on a large-area Si substrate by direct reaction of gallium with ammonia using
InCl3 as a catalyst. The morphology and microstructure of the resulting products were characterized using a field-emission scanning
electron microscope (SEM), a high-resolution transmission electron microscope, and X-ray diffraction (XRD). XRD and electron
diffraction revealed that the nanowires are of a hexagonal GaN phase with the wurtzite structure. The SEM study showed that
the nanowires are straight and have a smooth morphology with lengths up to 500 μm. The present results reveal that InCl3 is an optimal catalyst in GaN nanowire production.
Received: 2 April 2002 / Accepted: 12 April 2002 / Published online: 19 July 2002 相似文献
8.
C.F. Zhu W.K. Fong B.H. Leung C. Surya 《Applied Physics A: Materials Science & Processing》2001,72(4):495-497
High-quality GaN thin films are grown by rf-plasma assisted molecular beam epitaxy. The quality of the GaN epitaxial layer
is significantly improved by using an intermediate-temperature GaN buffer layer (ITBL) in addition to a conventional 20-nm-thick
low-temperature buffer layer. The GaN epitaxial layers demonstrate systematic improvements in the electron mobility increasing
from 82 cm2 V-1 s-1, for films grown with just the low-temperature buffer layer, to about 380 cm2 V-1 s-1 for films grown with an ITBL of thickness 800 nm. The photoluminescence also indicates systematic improvements in the intensity
and the full-width-half-maximum with the use of ITBL. Photoreflectance spectra are measured from the GaN films. Detailed analyses
of the excitonic transition energy demonstrate that the residual strain relaxes rapidly with the use of ITBL, which is attributed
to the observed improvements in the mobility and the PL spectra.
Received: 30 November 2000 / Accepted: 4 December 2000 / Published online: 9 February 2001 相似文献
9.
A transport theory for atomic matter waves in low-dimensional waveguides is outlined. The thermal fluctuation spectrum of
magnetic near fields leaking out of metallic microstructures is estimated. The corresponding scattering rate for paramagnetic
atoms turns out to be quite large in micrometer-sized waveguides (approx. 100 /s). Analytical estimates for the heating and
decoherence of a cold atom cloud are given. We finally discuss numerical and analytical results for the scattering from static
potential imperfections and the ensuing spatial diffusion process.
Received: 17 July 2000 / Published online: 30 November 2000 相似文献
10.
K.-H. Shim M.C. Paek B.T. Lee C. Kim J.Y. Kang 《Applied Physics A: Materials Science & Processing》2001,72(4):471-474
Effects of thermal treatments on the electrical properties and microstructures of indium–tin oxide (ITO)/GaN contacts have
been investigated using a rf-magnetron sputter deposition followed by rapid thermal annealing. ITO films annealed at 800 °C
revealed Schottky contact characteristics with a barrier height corresponding to ITO’s work function of 4.62 eV. The evolution
of electrical properties of ITO/GaN contacts was attributed to the preferential regrowth of In2O3 (222)//GaN (0001) with an ideal metal–semiconductor Schottky contact. The feasible use of ITO/GaN as a transparent Schottky
contact would be realized by the enhanced regrowth of In2O3 at high temperature.
Received: 1 September 2000 / Accepted: 15 November 2000 / Published online: 28 February 2001 相似文献
11.
Yinglong Huang Chengshan Xue Huizhao Zhuang Haibo Sun Dongdong Zhang Ying Wang Zouping Wang Yongfu Guo 《Superlattices and Microstructures》2009,45(6):514-519
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. 相似文献
12.
Li Yang Xing Zhang Ru Huang Guoyan Zhang Chengshan Xue 《Physica E: Low-dimensional Systems and Nanostructures》2005,25(4):853
Straight and smooth GaN nanowires were synthesized on quartz substrates through the direct reaction of Ga2O3 thin films with flowing ammonia in a horizontal oven without using a template or catalyst. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM) and photoluminescence (PL) were used to characterize the samples. The straight and smooth cylindrical nanostructures are high quality single crystalline hexagonal wurtzite GaN nanowires with diameters ranging from 5 to 30 nm and lengths up to 20 μm. The near-band-edge emission peak located at 367 nm was observed at room temperature. 相似文献
13.
Ying Wang Huizhao Zhuang Zouping Wang Dongdong Zhang Yinglong Huang Wenjun Liu 《Applied Surface Science》2009,255(17):7719-7722
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. 相似文献
14.
Various domain boundaries that are found in epitaxial Wurtzite GaN films were studied by molecular dynamics simulation. The
Ewald summation algorithm and Keating potential model are adopted to calculate the long-range Coulomb interaction and the
short-range bonding force in the semiconductor system, respectively. The research results show that the domain formation energies
of (100) and (110) boundaries are significantly different. The latter ones have general quite higher formation energies than the formers.
The like-atom (i.e. atoms of the same kind) bonding domain boundaries (LABDB) have higher formation energies than their counterparts
of unlike-atom (i.e. atoms of different kinds) bonding domain boundaries (UABDB) in all GaN (100) and (110) interfaces. The UABDB structures are all stable while most of the LABDB are unstable. The advantage and the limitation
of Keating potential model in Molecular Dynamics simulation for covalent crystal are discussed.
Received: 7 April 1999 / Accepted: 1 November 1999 / Published online: 8 March 2000 相似文献
15.
Preparation and characterization of GaN films by radio frequency magnetron sputtering and carbonized-reaction technique 总被引:1,自引:0,他引:1
Radio frequency magnetron sputtering/post-carbonized-reaction technique was adopted to prepare good-quality GaN films on Al2O3(0 0 0 1) substrates. The sputtered Ga2O3 film doped with carbon was used as the precursor for GaN growth. X-ray diffraction (XRD) pattern reveals that the film consists of hexagonal wurtzite GaN. X-ray photoelectron spectroscopy (XPS) shows that no oxygen can be detected. Electrical and room-temperature photoluminescence measurements show that good-quality polycrystalline GaN films were successfully grown on Al2O3(0 0 0 1) substrates. 相似文献
16.
H. Leinen D. Glässner H. Metcalf R. Wynands D. Haubrich D. Meschede 《Applied physics. B, Lasers and optics》2000,70(4):567-571
We have characterized the spectroscopic properties of one of the first samples of blue-emitting diode lasers based on GaN.
With such a laser diode operated inside a standard extended cavity arrangement we find a mode-hop free tuning range of more
than 20 GHz and a linewidth of 10 MHz. Doppler-free spectroscopy on an indium atomic beam reveals the isotope shift between
the two major indium isotopes as well as efficient optical pumping.
Received: 8 November 1999 / Revised version: 31 January 2000 / Published online: 8 March 2000 相似文献
17.
S. Gu R. Zhang Y. Shi Y. Zheng L. Zhang T.F. Kuech 《Applied Physics A: Materials Science & Processing》2002,74(4):537-540
The initial stages and subsequent growth of GaN on sapphire using ZnO buffer layers is reported for the hydride vapor phase
epitaxy technique. A high gas-phase supersaturation in the growth ambient was used to favor a rapid initial growth on the
substrate. A subsequent growth step was employed under conditions that favor a high lateral growth rate in order to promote
the coalescence of the initial islands and provide optimal material properties. The specific gas-phase mole fractions of the
GaCl and NH3 at the growth front control both the vertical and lateral growth rates. The use of a two-step growth process in the GaN growth
leads to a controlled morphology and improved material properties for GaN materials when grown with a ZnO buffer layer. An
optimized set of growth conditions, utilizing this two-step process, was found to also improve the growth directly on sapphire
without a ZnO buffer layer.
Received: 8 November 2001 / Accepted: 14 November 2001 / Published online: 11 February 2002 相似文献
18.
采用超重力反应结晶法制备了纳米硫化锌粒子,并通过透射电子显微镜(TEM)、X射线粉末衍射仪(XRD)、X射线光电子能谱仪(XPS)、傅里叶红外光谱仪(FTIR)、紫外-可见光分光光度计(UV-Vis)和X射线能谱仪(EDX)对纳米硫化锌的形貌、结构、组成和光谱性能进行了细致分析。结果表明:超重力反应结晶法制备的纳米硫化锌粒子为球形,平均粒径为42 nm;XRD图谱表明纳米硫化锌呈现较好的闪锌矿晶型; XPS能谱表明纳米硫化锌的S(2p)的电子结合能为162.6 eV,Zn的2p3/2,2p1/2的电子结合能分别为1021.4, 1044.6eV。红外光谱研究表明纳米硫化锌在400~4 000cm-1范围内具有良好的红外透过率。紫外-可见光谱研究发现纳米硫化锌在200~340nm的紫外区域有较强的吸收,其禁带宽度为3.57eV。EDX能谱表明该法制备的纳米硫化锌具有较高的纯度。 相似文献
19.
Ö.F. Yüksel B.M. Basol H. Safak H. Karabiyik 《Applied Physics A: Materials Science & Processing》2001,73(3):387-389
Optical absorption spectra of CuInSe2 chalcopyrite semiconductor films prepared using a two-stage technique were investigated. In addition to absorption measurements,
energy-dispersive analysis of X-rays (EDAX) and X-ray diffraction measurements (XRD) were also performed. Direct bandgap energy
values for the CuInSe2 films were derived from the variation of (αhν)2 with energy. All the measurements were performed on samples with various Cu/In ratios. It was determined from the absorption
measurements that the materials have strong absorption at the fundamental band edge. The Eg values showed an increasing trend with decreasing Cu/In ratios.
Received: 26 May 2000 / Accepted: 31 October 2000 / Published online: 10 January 2001 相似文献
20.
A new method for the synthesis of tridymite is reported in this article. When amorphous SiO2 is treated with ethylene glycol for 3 h at 196°C and then filtered and washed with distilled water, tridymite is obtained. The transmission electron microscopy equipped with energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) are used to characterize the crystal materials. The EDX shows the material is pure silica and The XRD pattern shows this silica is tridymite phase. In order to study the formation process of tridymite, all sorts of reaction conditions are discussed in detail. The products obtained at different conditions are characterized by XRD techniques. Finally, a reasonable mechanism is proposed. 相似文献