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ABSTRACT: In this paper, five-period InGaN/GaN multiple quantum well green light-emitting diodes (LEDs) were grown by metal organic chemical vapor deposition with 405-nm light beam in situ monitoring system. Based on the signal of 405-nm in situ monitoring system, the related information of growth rate, indium composition and interfacial quality of each InGaN/GaN QW were obtained, and thus, the growth conditions and structural parameters were optimized to grow high-quality InGaN/GaN green LED structure. Finally, a green LED with a wavelength of 509 nm was fabricated under the optimal parameters, which was also proved by ex situ characterization such as high-resolution X-ray diffraction, photoluminescence, and electroluminescence. The results demonstrated that short-wavelength in situ monitoring system was a quick and non-destroyed tool to provide the growth information on InGaN/GaN, which would accelerate the research and development of GaN-based green LEDs.
Nanoscale Research Letters 05/2012; 7(1):282. · 2.73 Impact Factor
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ABSTRACT: Realization of highly responsivity UV detectors is a critical challenge for accelerating the application of UV detectors. Exploiting nanoplasmonic enhancement, Ag nanoparticles have been formed on the GaN surface and the responsivity of the GaN UV detector has been enhanced about 30 times compared with that without Ag nanoparticles.
Advanced Materials 01/2012; 24(6):845-9. · 13.88 Impact Factor
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ABSTRACT: ABSTRACT: To improve the field emission performance of carbon nanotubes (CNTs), a simple and low-cost method was adopted in this article. We introduced copper particles for decorating the CNTs so as to form copper particle-CNT composites. The composites were fabricated by electrophoretic deposition technique which produced copper metallic particles localized on the outer wall of CNTs and deposited them onto indium tin oxide (ITO) electrode. The results showed that the conductivity increased from 10-5 to 4 × 10-5 S while the turn-on field was reduced from 3.4 to 2.2 V/μm. Moreover, the field emission current tended to be undiminished after continuous emission for 24 h. The reasons were summarized that introducing copper metallic particles to decorate CNTs could increase the surface roughness of the CNTs which was beneficial to field emission, restrain field emission current from saturating when the applied electric field was above the critical field. In addition, it could also improve the electrical contact by increasing the contact area between CNT and ITO electrode that was beneficial to the electron transport and avoided instable electron emission caused by thermal injury of CNTs.
Nanoscale Research Letters 10/2011; 6:537. · 2.73 Impact Factor
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ABSTRACT: The influence of threading dislocations on the properties of GaN-based metal-semiconductor-metal (MSM) ultraviolet photodetectors was investigated. It was found that screw dislocations had a strong influence on the dark current of the photodetectors, while edge dislocations had the predominant effect on their responsivity. The dark current increased as the screw dislocation density increased due to their lowering of the Schottky barrier height. However, the responsivity of the photodetectors decreased with increasing edge dislocation density because of the dangling bonds along those edge dislocation lines which enhance the recombination of photogenerated electron-hole pairs. The results suggest that reducing both the screw and edge dislocation densities is an effective way to improve the photoelectric property of GaN-based MSM ultraviolet photodetectors.
Applied Physics Letters 01/2011; 98(1):011108-011108-3. · 3.84 Impact Factor
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Lianzhen Cao,
Hong Jiang,
Hang Song, Zhiming Li,
Xia Liu,
Wanguo Guo,
Dawei Yan,
Xiaojuan Sun,
Haifeng Zhao,
Guoqing Miao,
Dabing Li
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ABSTRACT: Novel ordered aloetic-shaped SiC nanowires were synthesized on a Si (100) substrate by reacting methane with silicon dioxide using iron as a catalyst. Their structure and chemical composition were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The wires have a tapered aloetic structure with a top diameter about 50-80 nm and a length about 10 microm. The field emission properties of the aloetic nanowires were investigated. A stable emission with current density of 0.525 mA/cm2 at an applied electric field of 2.2 V/microm and a low turn-on electric fields of 1.4 V/microm were observed. The excellent field emission properties indicate that the aloetic-shaped SiC nanowires may have potential applications in flat panel displays and electron field-emitting devices.
Journal of Nanoscience and Nanotechnology 03/2010; 10(3):2104-7. · 1.56 Impact Factor
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Microelectronics Journal. 01/2008; 39:782-785.
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Microelectronics Journal. 01/2007; 38:398-400.
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ABSTRACT: Multi-wall carbon nanotubes were deposited on the patterned silicon substrates using electrophoretic deposition. The surface images of carbon nanotubes on substrate were observed by scanning electron microscopy. Field emission properties have been tested with a diode structure in a vacuum chamber below 5×10<sup>-4</sup> Pa. The emission area measured is 1.0mm. Emission current density up to 30mA/cm at an electric field of 8V/μm has been obtained. Patterned deposition of carbon nanotubes by electrophoresis is a potential method to prepare field emission arrays.
Vacuum Electron Sources Conference, 2004. Proceedings. IVESC 2004. The 5th International; 10/2004
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ABSTRACT: InAs0.6P0.4 epilayers grown on InP (100) substrates using two-step growth method by LP-MOCVD were investigated. A low temperature (450 °C) In0.18Ga0.82As buffer layer was introduced to relax the lattice mismatch between the InAs0.6P0.4 epilayer and the InP substrate. The influence of In0.18Ga0.82As buffer layer thickness and epilayer’s growth temperature on crystalline quality of InAs0.6P0.4 epilayer was characterized by Scanning electron microscopy, X-ray diffraction, Hall measurements, Transmission electron microscopy and Photoluminescence. The experimental results showed that the crystalline quality of InAs0.6P0.4 epilayers could be greatly improved by optimizing the In0.82Ga0.18As buffer layer thicknesses and the InAs0.6P0.4 epilayer’s growth temperatures. It was found that, when In0.82Ga0.18As buffer layer thickness was 100 nm and InAs0.6P0.4 epilayer’s growth temperature was 580 °C, the InAs0.6P0.4 epilayer exhibited the best crystalline quality and properties.Highlights► InAs0.6P0.4 materials have been prepared by two-step growth method. ► The quality of InAs0.6P0.4 can be improved with a 100 nm InGaAs buffer layer. ► The quality of InAs0.6P0.4 can be improved when epilayer is grown at 530 °C. ► The optimum experimental conditions of preparing InAs0.6P0.4 have been obtained.
Solid State Communications 151(12):904-907. · 1.65 Impact Factor
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ABSTRACT: Catalyst-free InP nanowires were grown on Si (1 0 0) substrates by metal organic chemical vapor deposition. In this method, in situ deposited In droplets are seeds of the InP nanowires growth. In order to control the growth of epitaxial InP nanowires, a detailed investigation on the growth related aspects such as the In droplets deposition time, growth temperature, and V/III ratio has been made. The experimental results indicate that the diameter, shape, and length of the nanowires can be controlled by growth conditions.
Journal of Alloys and Compounds 479:832-834. · 2.29 Impact Factor
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ABSTRACT: Catalyst-free InP nanowires were grown on Si (1 0 0) substrates by metal-organic chemical vapor deposition. Morphology, crystal structure, photoluminescence, and Raman scattering properties of the nanowires were investigated. Most nanowires are long and straight; the angles between the nanowires and the Si substrate are diverse. The photoluminescence peak shows blue-shift from the band gap energy of bulk InP. Both the blue-shift of photoluminescence peak and the full width at half-maximum of photoluminescence spectrum increase with decreasing nanowires growth temperature. Due to laser-induced heating, the TO and LO phonon peaks of the nanowires reveal downshift and asymmetric broadening compared with those of bulk InP at room temperature.
Physica E: Low-dimensional Systems and Nanostructures.
