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  • 1
    Electronic Resource
    Electronic Resource
    Optical and Surface Morphological Study of GaN Nanocolumn Grown on Gallium Coated Si by Molecular Beam Epitaxy (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 31 (Nov. 2007), p. 120-122 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Vertically aligned GaN nanocolumn arrays were grown by molecular beam epitaxy onGallium coated silicon substrate. The dense packing of the NCs gives them the appearance of acontinuous film in surface view, but cross-sectional analysis shows them to be isolatednanostructures. The GaN nanocolumns have uniform diameters of 85 nm, lengths up to 720 nm andpossess a pyramid like tip. Photoluminescence measurements of NCs show excitonic emission witha dominant, narrow peak centered at 363 nm and FWHM of 68 meV. From the Raman spectrum,peaks at 566.9 and 730 cm-1 are assigned to the E2 and A1(LO) GaN phonons modes which clearlyindicates that the grown nanocolumns are highly crystalline. The grown nanocolumns are highlyoriented and perpendicular to the growth surface
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.31.120.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Growth of GaN Nano-Column on Si (111) Substrate Using Au+Ga Alloy Seeding by Pulsed Flow Method Using MOCVD (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 31 (Nov. 2007), p. 108-110 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Vertical GaN nano-columns arrays were grown on Au-coated silicon (111) substrate byAu+Ga alloy seeding method and pulsed flow of Gallium and ammonia using metalorganicchemical vapor deposition (MOCVD). A gold thin film was deposited on Si using an ion coatingsystem. The Au coated Si substrate was annealed at 800 oC under hydrogen ambient for 5 min. Thepre-deposition of gallium and nitrogen was performed for 60 sec to form Au+Ga and nitrogen solidsolution, which acts as the initial nucleation islands. Then Gallium and ammonia were let in pulsemethod. Scanning electron microscopy (SEM) image reveals a vertical growth and cylindrical inshape GaN nano-column. From the sharp PL peak intensity it is clearly seen that the dislocationdensity is reduced considerably and the optical quality of the nano-column is improved
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.31.108.pdf
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  • 3
    Electronic Resource
    Electronic Resource
    Growth and Evaluation of GaN Grown on Patterned Sapphire Substrates (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 29-30 (Nov. 2007), p. 351-354 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: We report the microstructure and optical properties of gallium nitride (GaN) epilayersgrown on lens shape patterned sapphire substrate (PSS) using metalorganic chemical vapordeposition (MOCVD) for various growth times. A lens shaped pattern was used to reduce thethreading dislocation density and to improve optical emission efficiency. A scanning electronmicroscope (SEM) image shows flat and smooth surface of GaN grown on PSS at 80 min which couldbe achieved by lateral growth from the trench region. From the DCXRD spectra, full width at halfmaximun (FWHM) value was decreased with increasing growth time. FWHM of the sample grown at80 min was 473.5 arc sec. This indicates there is an improvement in crystalline quality of the GaNgrown on PSS as the growth time increases. From photoluminescence (PL) spectra, an increase inband edge emission intensity and a decrease in defect related yellow luminescence was observed forGaN on PSS as the growth time increased. From the PL spectra, FWHM was 82.2 meV at peakposition 363.9 nm for the sample grown for 80 min. It is clearly seen that the threading dislocationscan be reduced by lateral growth improving the light emission efficiency by internal light reflection onthe lens surface for GaN grown on PSS
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.29-30.351.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Characteristics Comparison between GaN Epilayers Grown on Patterned and Unpatterned Sapphire Substrate (0001) (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 29-30 (Nov. 2007), p. 355-358 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: GaN epilayers were grown on lens shaped patterned sapphire substrate (PSS) (0001) andunpatterned sapphire substrate (UPSS) (0001) by metal-organic chemical vapor deposition(MOCVD). The quality of the grown GaN epilayers on the PSS and UPSS were compared. Structuralcharacteristics, surface morphology and optical properties of the GaN epilayers were investigatedusing double crystal X-ray diffraction (DCXRD), atomic force microscopy (AFM), scanning electronmicroscopy (SEM) and photoluminescence (PL). A lens shaped pattern was formed on the sapphiresubstrate to reduce threading dislocation (TD) density and also to improve the optical emissionefficiency by internal reflection on the lens. Scanning electron microscopy images show the growth ofGaN epilayers at various times. Full coalescence is observed at a growth time of 80 min. It is seenfrom the DCXRD rocking spectrum that full width at half maximum (FWHM) of the GaN grown onPSS was 438.7 arcsec which is less than UPSS value. The lower value of FWHM indicates that thecrystalline quality of the GaN epilayers grown on PSS is improved compared to GaN grown on UPSS.It is clearly seen from the AFM images that the dislocation density is less for the GaN grown on PSS.A strong and sharp photoluminescence (PL) band edge emission was observed for the GaN grown onPSS compared to UPSS. Defect related yellow luminescence was observed for GaN grown on UPSSwhich did not appear for PSS. The FWHM at the 364.3 nm peak position was evaluated to be 50.7meV from the PL spectra for GaN grown on PSS. The above result indicates GaN epilayers can begrown on PSS with low TD density and will be useful for optical emission
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.29-30.355.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Raman study of Epitaxial lateral Overgrowth of GaN on Patterned Sapphire Substrate (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 31 (Nov. 2007), p. 111-113 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Structural and optical properties of gallium nitride (GaN) epilayers grown on lens shapepatterned sapphire substrate (PSS) using metalorganic chemical vapor deposition (MOCVD) forvarious growth times were evaluated. From Raman spectra, a blue shift and reduction in the FWHMof Raman modes of GaN grown on PSS were observed when compared to GaN grown onunpatterend sapphire substrate (UPSS). From the DCXRD spectra, full width at half maximum(FWHM) value was decreased with increasing growth time. FWHM of the sample grown at 80 minwas 473.5 arc sec. This indicates that there is an improvement in crystalline quality of the GaNgrown on PSS as the growth time increases. From photoluminescence (PL) spectra, an increase inband edge emission intensity and a decrease in defect related yellow luminescence were observedfor GaN on PSS as the growth time increased
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.31.111.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    Growth and Characterization of GaN Nano-Column Grown on Si (111) Substrate Using Au+Ga Alloy Seeding Method by MOCVD (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 124-126 (June 2007), p. 113-118 
    Details
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: We have studied the Au+Ga alloy seeding method. Single-crystal GaN nano-column arrays weregrown using metalorganic chemical vapor deposition (MOCVD) and their properties were investigated asa function of the growth parameters and Au thin film thickness. Au-coated Si(111) substrates were usedfor the growth of GaN nano-columns. The diameter and length of as-grown nano-column ranged from100 to 500 nm and 1 to 5 μm, respectively. The morphology of the columns was investigated usingscanning electron microscopy. Energy dispersive X-ray spectroscopy and photoluminescence were usedfor evaluating of its qualitative analysis and to evaluate the optical properties, respectively. Twoimportant growth parameters were considered, the thickness of the Au thin film and the gallium flow rate.The density and tendency of the nano-columns depend on each of these growth parameters. It is believedthat the catalytic activity of gold is determined by the size of the Au+Ga solid solution particles, andsmaller Au+Ga clusters showed significant reactivity in the growth of one-dimensional GaN nanostructures
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/23/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.124-126.113.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    Role of the COOH-terminal pro-sequence of aqualysin I (a heat-stable serine protease) in its extracellular secretion by Thermus thermophilus (1997)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 157 (1997), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Aqualysin I is a subtilisin-type serine protease secreted into the medium by Thermus aquaticus YT-1. Thermus thermophilus cells harboring a plasmid for the aqualysin I precursor secreted pro-aqualysin I with the C-terminal pro-sequence into the culture medium, and the precursor was then processed to the mature enzyme during the cultivation. However, the extracellular levels of aqualysin I in T. thermophilus cells harboring plasmids for deletion mutants as to the C-terminal pro-sequence were about 10–20% in comparison with the level of wild-type. Only the mature enzyme could be detected in the medium, while pro-aqualysin I with the C-terminal pro-sequence could not. These results suggest that the C-terminal pro-sequence of aqualysin I plays an important role in the extracellular secretion of aqualysin I.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1997.tb12750.x
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  • 8
    Electronic Resource
    Electronic Resource
    Interface chemistry and electrical properties of SrVO3/LaAlO3 heterostructures (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 7056-7059 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: SrVO3 films were grown by laser molecular beam epitaxy on LaAlO3 substrates. For a 10-nm-thick film, its resistivity could be reduced by a factor of 4 by inserting a single La–O atomic layer on an oxygen-annealed LaAlO3 substrate. X-ray diffraction and x-ray photoelectron spectroscopy measurements revealed that oxygen defect concentrations could be varied significantly by controlling the substrate terminations, i.e., interface chemistry. It was suggested that the interface chemistry could influence formation of extended defects and result in changes in electrical properties. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1326896
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  • 9
    Electronic Resource
    Electronic Resource
    Roles of the first atomic layers in growth of SrTiO3 films on LaAlO3 substrates (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2176-2178 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Growth behaviors of SrTiO3/LaAlO3 films could be varied substantially by controlling terminating atomic layers of the substrates. In a film on the LaO-terminated substrate, strain-induced roughening was observed. In a film on the AlO2-terminated substrate, the first atomic layer of the interface seemed to have lots of defects. However, the stress became quickly relaxed, so a SrTiO3 film could be grown in a layer-by-layer mode after a few monolayers. All these observations could be explained in terms of chemical matching between the atomic layers at the interface. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123792
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  • 10
    Electronic Resource
    Electronic Resource
    Correlation of Thickness with the Photocatalytic Characteristic of TiO〈sub〉2〈/sub〉 Thin Films (2005)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 486-487 (June 2005), p. 65-68 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: 5, 10, and 30 nm thickness of transparent TiO2 thin films were fabricated using sol-gel process, and the influence of film thickness on the photocatalytic property was investigated. The increase in film thickness was found to enhance the photocatalytic property of the films. Photocatalytic properties of each film were estimated by decomposition of stearic acid. The amount of decomposed stearic acid increased with film thickness (5 - 30 nm). For the case of 30 nm thickness film, the stearic acid was decomposed perfectly in twelve minutes. UV-vis spectra and photocurrents of each film clearly showed that the photoactivities of TiO2 films were related to the amount of absorbed UV light and band gap shift
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/10/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.486-487.65.pdf
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