共查询到20条相似文献,搜索用时 62 毫秒
1.
High-quality thick GaN films without cracks were achieved by using a new nozzle structure in the reactor grown by the hydride vapor phase epitaxy on sapphire substrates. Optical contrast microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray double diffraction (XRD) and cathodoluminescence (CL) were carried out to reveal the surface, crystal and optical properties of the GaN epilayer. It was found that the nozzle structure in the reactor has a large effect on the growth rate, surface flat, crystal quality, and the uniformity of the growth. Compared with the old one, the new nozzle structure (denoted as multi-layers nozzle) can improve dramatically the properties of thick GaN. Mirror, colorless and flat GaN thick film was obtained and its (0 0 0 2) FWHM results were reduced from 1000 to 300 arcsec when the new nozzle was used. AFM result revealed a step flow growth mode for GaN layer with the new nozzle. Room-temperature CL spectra on the GaN films showed a strong near-band-edge peak for the new nozzle, but there is only weak emitting peak for the old nozzle. New nozzle structure can improve the uniform of flow field near the surface of substrates compared with the old one, which leads to the improvement of properties of GaN thick film by hydride vapor phase epitaxy (HVPE). 相似文献
2.
Template-based nanoscale epitaxy has been explored to realize high-quality GaN on Si(1 1 1) substrates. We have employed polystyrene-based nanosphere lithography to form the nano-hole array patterns on GaN/Si(1 1 1) template and then, subsequent regrowth of GaN is carried out by metalorganic chemical vapor deposition (MOCVD). During the initial growth stage of GaN on such nanopatterned substrates, we have observed formation of nanoislands with hexagonal pyramid shape due to selective area epitaxy. With further epitaxial regrowth, these nanoislands coalesce and form continuous GaN film. The overgrown GaN on patterned and non-patterned regions is characterized by high-resolution X-ray diffraction (HRXRD) and high-spatial resolution optical spectroscopic methods. Micro-photoluminescence (PL), micro-Raman scattering and scanning electron microscopy (SEM) have been used to assess the microstructural and optical properties of GaN. Combined PL and Raman data analyses show improved optical quality when compared to GaN simultaneously grown on non-patterned bulk Si(1 1 1). Such thicker GaN templates would be useful to achieve III-nitride-based opto- and electronic devices integrated on Si substrates. 相似文献
3.
Effect of Reactor Pressure on Qualities of GaN Layers Grown by Hydride Vapour Phase Epitaxy
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The influence of reactor pressure on GaN layers grown by hydride vapour phase epitaxy (HVPE) is investigated. By decreasing the reactor pressure from0. 7 to 0.5 mm, the GaN layer growth mode changes from the island-like one to the step flow. The improvements in structural and optical properties and surface morphology of GaN layers are observed in the step flow growth mode. The results clearly indicate that the reactor pressure, similarly to the growth temperature, is One of the important parameters to influence the qualities of GaN epilayers grown by HVPE, due to the change of growth mode. 相似文献
4.
We have presented a theoretical study on electron resonant Raman scattering (ERRS) process associated with the bulk longitudinal optical (LO), surface optical (SO) and quasi-confined (QC) phonon modes in a free-standing wurtzite nanowire (NW). We consider the Fröhlich electron–phonon interaction in the framework of the dielectric continuum model. Numerical calculations on the GaN material reveal that differential cross-section (DCS) is sensitive to the wire size. The bulk LO and high-frequency quasi-confined (QC+) phonons make main contributions to the DCS and the impact of the SO phonon can be negligible in the ERRS process. Moreover, scattering intensity of the bulk LO phonon is strongly enhanced as the incident photon energy approaches the energy band-gap of the GaN. 相似文献
5.
GaN nanowires have been successfully synthesized on Si(1 1 1) substrates by magnetron sputtering through ammoniating Ga2O3/Cr thin films at 950 °C. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), FT-IR spectrophotometer, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (TEM), and photoluminescence (PL) spectrum were carried out to characterize the microstructure, morphology, and optical properties of GaN samples. The results demonstrate that the nanowires are single-crystal GaN with hexagonal wurtzite structure and high-quality crystalline, have the size of 30-80 nm in diameter and several tens of microns in length with good emission properties. The growth direction of GaN nanowires is perpendicular to the fringe of (1 0 1) plane. The growth mechanism of GaN nanowires is also discussed in detail. 相似文献
6.
A. Guillén-Cervantes Z. Rivera-ÁlvarezM. López-López A. Ponce-PedrazaC. Guarneros V.M. Sánchez-Reséndiz 《Applied Surface Science》2011,258(3):1267-1271
GaN thin films grown by MOCVD on (0 0 0 1) Al2O3 substrates at different growth pressures were characterized by field-emission scanning electron microscopy, atomic force microscopy, micro-Raman, and photoluminescence at room temperature. It was found that there is an optimum pressure of 76 Torr at which the structural and optical properties of the GaN samples are superior. On the other hand samples grown at higher pressure exhibited hexagonal surface pits and surface spirals. The results showed that the growth pressure strongly influences the morphology, and significantly affects the structural and optical properties of the GaN epilayers. 相似文献
7.
A. Yamada K.P. Ho T. Maruyama K. Akimoto 《Applied Physics A: Materials Science & Processing》1999,69(1):89-92
The feasibility of MoS2 layered compound as a substrate for GaN growth was investigated. GaN films were successfully grown on MoS2 by plasma-enhanced molecular beam epitaxy and the crystal quality of GaN on MoS2 was compared with that on Al2O3. For GaN grown on MoS2 substrate, it was found that the surface flatness observed by atomic force microscopy, stress in the film measured by Raman
spectroscopy, optical properties measured by photoluminescence spectroscopy, and threading dislocation density observed by
transmission electron microscopy show superior properties compared with that grown on Al2O3. These results suggest the layered compound such as MoS2, which has no dangling bonds on the surface and has lattice mismatching of 0.9% to GaN, has high potential for a substrate
of GaN growth.
Received: 1 March 1999 / Accepted: 8 March 1999 / Published online: 26 May 1999 相似文献
8.
This paper presents the investigation of the properties of GaN nanowires synthesized from Ni-catalyzed chemical vapour deposition method under various growth temperatures. The influence of the growth temperatures on the morphological, structural and optical characteristics of the synthesized GaN nanowires was investigated in this work. Field-emission scanning electron microscopy images revealed that the 950 °C was the optimal growth temperature for synthesizing uniform, straight and smooth morphology of GaN nanowires. X-ray diffraction results demonstrated that the synthesized low dimensional GaN structures have the hexagonal wurtzite structure. Ultraviolet and blue emissions were detected from photoluminescence measurements. In addition, phonon replicas with the energy separation of 90 meV have been observed at the lower energy of the blue emission region in photoluminescence spectra. 相似文献
9.
Influence of AlN buffer layer thickness on structural properties of GaN epilayer grown on Si (111) substrate with AlGaN interlayer
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We present the growth of GaN epilayer on Si (111)
substrate with a single AlGaN interlayer sandwiched between the GaN
epilayer and AlN buffer layer by using the metalorganic chemical
vapour deposition. The influence of the AlN buffer layer thickness
on structural properties of the GaN epilayer has been investigated
by scanning electron microscopy, atomic force microscopy, optical
microscopy and high-resolution x-ray diffraction. It is found that
an AlN buffer layer with the appropriate thickness plays an important
role in increasing compressive strain and improving crystal quality
during the growth of AlGaN interlayer, which can introduce a more
compressive strain into the subsequent grown GaN layer, and
reduce the crack density and threading dislocation density in GaN
film. 相似文献
10.
Sabit Korçak Süleyman Çörekçi Hongbo Yu Semran Sa?lam Ekmel Özbay 《Surface science》2007,601(18):3892-3897
The structural and optical properties of an InxGa1−xN/GaN multi-quantum well (MQW) were investigated by using X-ray diffraction (XRD), atomic force microscopy (AFM), spectroscopic ellipsometry (SE) and photoluminescence (PL). The MQW structure was grown on c-plane (0 0 0 1)-faced sapphire substrates in a low pressure metalorganic chemical vapor deposition (MOCVD) reactor. The room temperature photoluminescence spectrum exhibited a blue emission at 2.84 eV and a much weaker and broader yellow emission band with a maximum at about 2.30 eV. In addition, the optical gaps and the In concentration of the structure were estimated by direct interpretation of the pseudo-dielectric function spectrum. It was found that the crystal quality of the InGaN epilayer is strongly related with the Si doped GaN layer grown at a high temperature of 1090 °C. The experimental results show that the growth MQW on the high-temperature (HT) GaN buffer layer on the GaN nucleation layer (NL) can be designated as a method that provides a high performance InGaN blue light-emitting diode (LED) structure. 相似文献
11.
L.X. Zhao G.W. Meng X.S. Peng X.Y. Zhang L.D. Zhang 《Applied Physics A: Materials Science & Processing》2002,74(4):587-590
Large quantities of gallium nitride (GaN) nanorods have been synthesized via direct reaction of metallic gallium vapor with
flowing ammonia at 970 °C in a quartz tube. The nanorods have been confirmed as crystalline wurzite GaN by powder X-ray diffraction,
selected-area electron diffraction and X-ray photoelectron spectrometry. Transmission electron microscopy and scanning electron
microscopy reveal that the nanorods are straight and uniform, with diameters ranging from 40 nm to 150 nm and lengths up to
hundreds of micrometers. The growth mechanism is discussed briefly. Photoluminescence measurements on bulk GaN nanorods at
room temperature show two strong peaks at 377 nm (3.28 eV) and 360 nm (3.44 eV) attributed to the zero-phonon donor-acceptor
pair transition and the donor-bound exciton, respectively.
Received: 19 April 2001 / Accepted: 10 May 2001 / Published online: 20 June 2001 相似文献
12.
The effects of sapphire nitridation on GaN growth by metalorganic chemical vapour deposition
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In situ optical reflectivity measurements are employed to monitor the GaN epilayer growth process above a low-temperature GaN buffer layer on a c-plane sapphire substrate by metalorganic chemical vapour deposition. It is found that the lateral growth of the GaN islands and their coalescence are promoted in the initial growth stage if optimized nitridation time and temperature are selected when the substrate is pre-exposed to ammonia. As confirmed by atomic force microscopy observations, the quality of the GaN epilayers is closely dependent on the surface morphology of the nitridated buffer layer, especially grain size and nucleation density. 相似文献
13.
Jun Beom Park Nam-Jung Kim Yong-Jin Kim Sang-Hyup Lee Gyu-Chul Yi 《Current Applied Physics》2014,14(11):1437-1442
We report the growth of high-areal-density GaN nanowires on large-size graphene films using a nickel (Ni) catalyst-assisted vapor-liquid-solid (VLS) method. Before the nanowire growth, the graphene films were prepared on copper foils using hot-wall chemical vapor deposition and transferred onto SiO2/Si substrates. Then, for catalyst-assisted VLS growth, Ni catalyst layers with thickness of a few nanometers were deposited on the graphene-coated substrates using a thermal evaporator. We investigated the effect of the Ni catalyst thickness on the formation of GaN nanowires. Furthermore, the structural and optical characteristics of GaN nanowires were investigated using X-ray diffraction, transmission electron microscopy, and photoluminescence spectroscopy. The GaN nanowires grown on graphene films were transferred onto polymer substrates using a simple lift-off method for applications as flexible photocatalysts. Photocatalysis activities of the GaN nanowires prepared on the flexible polymer substrates were investigated under bending conditions. 相似文献
14.
S. A. Smirnov V. N. Panteleev Yu. V. Zhilyaev S. N. Rodin A. S. Segal Yu. N. Makarov A. V. Butashin 《Technical Physics》2008,53(12):1602-1605
Chloride epitaxy of GaN layers in a horizontal reactor is studied numerically. The steady 3D fluxes of the gas mixture in
the reactor are simulated with allowance for heterogeneous reactions on the substrate (growth of epitaxial GaN layers) and
on the reactor walls (growth of a polycrystalline GaN deposit). Experimental data on the growth rate distribution for polycrystalline
and epitaxial GaN layers are explained. It is shown that, if the diameter of the reactor is not large enough, the growth of
the deposit on the walls makes the GaN growth rate distribution over the substrate more nonuniform due to the parasitic diffusion
of reagents from the gas phase to the reactor walls. 相似文献
15.
16.
GaN dots were deposited on AlN underlayers by alternate supply of trimethylgallium (TMG) and ammonia (NH3) in an inductively heated quartz reactor operated at atmospheric pressure. Various growth parameters including deposition temperature, TMG admittance and pulse time between TMG and NH3 exposures were proposed to investigate the influence of growth parameters on the size distribution of GaN dots. It appears that GaN dots with uniform size distribution can be achieved under certain growth conditions. Based on the study of atomic force microscopy (AFM), high deposition temperature was found to be in favor of forming large GaN dots with small dot density. Decrement of TMG flow rate or reduction in the number of growth cycle tends to enable the formation of GaN dots with small dot sizes. The results of room temperature (RT) cathodoluminescence (CL) measurements of the GaN dots exhibit an emission peak at 3.735 eV. A remarkable blue shift of GaN dot emission was observed by reduced temperature photoluminescence (PL) measurements. 相似文献
17.
《中国物理 B》2020,(2)
Doping is essential in the growth of bulk GaN substrates,which could help control the electrical properties to meet the requirements of various types of GaN-based devices.The progresses in the growth of undoped,Si-doped,Ge-doped,Fedoped,and highly pure GaN by hydride vapor phase epitaxy(HVPE) are reviewed in this article.The growth technology and precursors of each type of doping are introduced.Besides,the influence of doping on the optical and electrical properties of GaN are presented in detail.Furthermore,the problems caused by doping,as well as the methods to solve them are also discussed.At last,highly pure GaN is briefly introduced,which points out a new way to realize high-purity semi-insulating(HPSI) GaN. 相似文献
18.
采用金属有机物化学淀积技术在不同倾角(0°—03°)的蓝宝石衬底上外延n型GaN.通过原子力显微镜观察到n型GaN均呈台阶流生长模式,02°和03°倾角衬底的n型GaN表面台阶朝向相同、分布均匀,明显地看到在0°倾角衬底的n型GaN表面由台阶重构直接导致的台阶朝向随机分布、疏密不匀的形貌.电子背散射分析表明,在0°倾角衬底的n型GaN外延层的应力随外延厚度增加而增加,而02°和03°倾角衬底的n型GaN外延层的应力没有明显的变化.电学和光学特性研究表明,02°和03°倾角衬底的n型GaN有较高的电子浓度和较低的黄光带与近带边强度之比.
关键词:
金属有机物化学淀积
氮化物
原子力显微镜
光致发光 相似文献
19.
Growth and characterization of GaN nanorods through ammoniating process by magnetron sputtering on Si(111) substrates 总被引:1,自引:0,他引:1
S. Xue H. Zhuang C. Xue L. Hu B. Li S. Zhang 《Applied Physics A: Materials Science & Processing》2007,87(4):645-649
GaN nanorods have been successfully synthesized on Si(111) substrates by magnetron sputtering through ammoniating Ga2O3/ZnO films at 950 °C in a quartz tube. The GaN nanorods are characterized by X-ray diffraction, scanning electron microscopy,
field-emission transmission electron microscopy, X-ray photoelectron spectroscopy and fluorescence spectrophotometry. The
results show that the nanorods have a pure hexagonal GaN wurtzite structure with lengths of about several micrometers and
diameters of about 200 nm, and the growth direction of the GaN nanorods is parallel to the (101) plane. The photoluminescence
spectrum indicates that the nanorods have a good emission property. Finally, the growth mechanism is also briefly discussed.
PACS 61.46.+w; 78.55.Cr; 81.15.Cd; 81.07.-b; 82.30.Hk 相似文献
20.
T. Yu. Chemekova O. V. Avdeev S. S. Nagalyuk E. N. Mokhov Kh. Khelava Yu. N. Makarov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2011,5(6):1136-1139
Currently, wafers of aluminum nitride cut from bulk aluminum nitride crystals (AlN) grown by sublimation are considered promising
substrates for obtaining light-emitting diode structures based on nitrides of the third group. In this study, the structural
characteristics and electrical properties of AlN, as a prospective substrate material for light-emitting diode heterostructures
based on AlGaN/GaN, were investigated. The substrate working surface ((0001) plane, Al-polar) was specifically prepared for
epitaxial growth using chemical-mechanical polishing. The surface roughness (“epi-ready”), as estimated by atomic force microscopy,
did not exceed 0.3 nm. 相似文献