Browsing by Author "Lin, Man-Ling"

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Broadband Omnidirectional Light Trapping in Gold-Decorated ZnO Nanopillar Arrays
(2017-04-05)
Chang, Yuan-Ming
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Lin, Man-Ling
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Lai, Tung-Yen
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Chen, Chang-Hung
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Lee, Hsin-Yi
The photoluminescence (PL) and reflectivity characteristics of zinc oxide nanopillars- (ZnO-NPs) grown on indium tin oxide (ITO)-coated glasses were investigated. The room temperature PL showed bright -white -light emission for the undoped ZnO-NPs grown at 600 degrees C, suggesting the close relation between the optical characteristic and "the growth conditions being, carried out for,obtaining the present ZnO-NPs. The reflectivity of the as -grown ZnO-NPs array was about, similar to 29% with the wavelength of the incident light ranging from 200 to 1800 nm. Nevertheless, the reflectance reduced significantly to less than 9.9% when a layer of gold (Au) was deposited on ZnO=NPg by sputtering for 5 min, corresponding to more than 65% reduction in Au -coated ZnQ-NPs (Au/ZnO-NPs). Moreover, the angle -resolved reflectance measurement's on the present Au/ZnO-NPs array show an omnidirectional light -trapping characteristic. These remarkable characteristics, broadband and omnidirectional light -trapping -of Ati/ZnO-NPs, are attributed to the extended effective optical path of the incident light due to subwavelength scattering resulting,from the presence of Au nanoparticics.
Field Emission Properties of Gold Nanoparticle-Decorated ZnO Nanopillars
(2012-12-01)
Chang, Yuan-Ming
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Lin, Man-Ling
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Lai, Tung-Yen
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Lee, Hsin-Yi
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Lin, Chih-Ming
The structural and optoelectronic properties of ZnO nanopillars (ZnO-NPs) grown on Si substrates by the vapor transport deposition method were investigated. In particular, by varying the deposition duration and hence the morphology of the vertically aligned ZnO-NPs, the resultant field emission characteristics were systematically compared. In addition to identifying the advantageous field emission properties exhibited in the pencil-like ZnO-NPs, we observed that by adhering Au nanoparticles on the surface of the ZnO-NPs the turn-on field and the maximum current density can be drastically improved from 3.15 V/mu m and 0.44 mA/cm(2) at 5 V/mu m for the best ZnO-NPs to 2.65 V/mu m and 2.11 mA/cm(2) at 5 V/mu m for Au/ZnO-NPs, respectively. The enhancement of field emission characteristics that resulted from Au-nanoparticle decoration is discussed on the basis of charge-transfer-induced band structure modifications.
High mobility transparent conductive Al-doped ZnO thin films by atomic layer deposition
(2017-12-15)
Lin, Man-Ling
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Huang, Jheng-Ming
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Ku, Ching-Shun
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Lin, Chih-Ming
;
Lee, Hsin-Yi
The effects of growth temperature on the microstructure, transport and optoelectronic properties of a series of Al-doped ZnO (AZO) films with thickness of similar to 30 nm deposited on polished silicon-(100) and glass substrates by the atomic layer deposition (ALD) were investigated. By adopting an in-situ doping growth scheme the critical length effect associated with adjacent Al2O3 layers commonly encountered in previous ALD growth schemes was avoided and effective Al-doping was achieved with the growth temperature ranging from 100 degrees C to 300 degrees C. Experimental results showed that, in general, increasing the growth temperature would result in much improved film crystallinity and carrier mobility, with the average transmittance in the visible wavelength range being exceeding 95% in all cases. In particular, for AZO films grown at 300 degrees C, an unprecedented mobility of 136 cm(2)V(-1)s(-1) was obtained, comparing to the typical values of 50-60 cm(2)V(-1)s(-1) reported previously. The resistivity of these 300 degrees C films (rho approximate to 6 x 10(-4) Omega-cm), nevertheless, is slightly higher than that of some highly-doped ZnO (rho approximate to 2 -4 x 10(-4) Omega-cm) prepared by sputtering methods. The secondary ion mass spectroscopy (SIMS) analyses revealed that hydrogen incorporation is the key in reducing the charge trap density and, hence, resulting in much enhanced carrier mobility. The present results promise a keen competitiveness of AZO with the indium tin oxide (ITO) film for thin-film-transistor (TFT) as well as in photovoltaic device applications. (C) 2017 Elsevier B.V. All rights reserved.
Tuning the magnetic properties of self-assembled BiFeO3-CoFe2O4 heteroepitaxy by magneto-structural coupling
(2016)
Amrillah, Tahta
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Vandrangi, Suresh K.
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Bitla, Yugandhar
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Do, Thi Hien
;
Liao, Sheng-Chieh
Magnetic and multiferroic nanocomposites with two distinct phases have been a topic of intense research for their profound potential applications in the field of spintronics. In addition to growing high-quality phase separated heteroepitaxial nanocomposites, the strain engineering that is conducive to enhance the tunability of material properties, in general, and the magnetic properties, in particular, is of utmost importance in exploring new possibilities. Here, we investigated the magneto-structural coupling between anti-ferromagnetic BiFeO3 (BFO) and ferrimagnetic CoFe2O4 (CFO) in self-assembled vertically aligned nanocomposites grown on LaAlO3 (LAO) and SrTiO3 (STO) substrates. We found that BFO exhibits tetragonal (T) and rhombohedral (R) structures as the stable phases and CFO has high magnetocrystalline anisotropy even in the form of nanocomposites. The temperature and magnetic field dependent magnetizations of T_ BFO-CFO/LAO and R_ BFO-CFO/STO nanocomposites primarily demonstrate the magnetoelastic coupling between these variants.