Browsing by Author "Lin, Tsung-Wu"

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Growth selectivity of hexagonal-boron nitride layers on Ni with various crystal orientations
(2012)
Lee, Yi-Hsien
;
Liu, Keng-Ku
;
Lu, Ang-Yu
;
Wu, Chih-Yu
;
Lin, Cheng-Te
Layered hexagonal-boron nitride (h-BN) films were synthesized by chemical vapor deposition (CVD) on Ni foils using ammonia borane as a precursor. Confocal Raman spectroscopy and electron backscatter diffraction (EBSD) were used to probe the effect of underlying Ni crystals with various orientations on growth behaviors of h-BN layers. The growth of the h-BN layers strongly depends on the Ni crystal orientations, where the growth rate of h-BN is larger on Ni(100)-like crystal surfaces but the growth on Ni(111)-like surfaces is not detectable, suggesting that Ni (100)-like facets are likely to promote the growth of h-BN compared with Ni (111)-like surfaces. The observation is in clear contrast to the reported growth of h-BN on Ni(111) in an ultrahigh vacuum environment. The as-grown CVD h-BN films on Ni exhibit a layered structure as revealed by atomic force microscopy (AFM). Thin h-BN layers are found on the Ni domain with a low growth rate. The observation of h-BN growth on various Ni grains may provide insights for the control of thickness, size and morphology of CVD h-BN films.
Label-free detection of DNA using novel organic-based electrolyte-insulator-semiconductor
(2010-08-15)
Lin, Tsung-Wu
;
Kekuda, Dhananjay
;
Chu, Chih-Wei
;
光電工程學系
;
Department of Photonics
In this study, we have constructed the first organic field effect sensor based on an electrolyte-insulator-semiconductor structure (OEIS) and applied this novel device to pH and DNA sensing. Variations in the insulator-electrolyte surface potential, which originate from either the change of the ionization states of the insulator surface groups or the binding of charged molecules to the insulator surface, modify the flat band voltage (V(FB)) of the OEIS sensor. The pH sensing experiments of OEIS sensor showed that the output signal linearly depended on pH solution in the range from pH 2 to pH 12, and an average sensitivity of 44.1 mV/pH was obtained. In the biosensing experiments, the absorption of positively charged poly-L-lysine on the insulator surface resulted in the reduction of the V(FB) value, whereas the subsequent binding of negatively charged single-stranded DNA probe (ssDNA) via electrostatic interaction increased the VFB value. Furthermore, the ssDNA-immobilized OEIS device was successfully used for the detection of DNA hybridization. The detection limit of complementary DNA was as low as 1 mu M, and the output signal of OEIS biosensor linearly increased with the logarithm of complementary DNA concentration in the range from 5 x 10(-5) to 10(-7) M. The easy and inexpensive fabrication of the OEIS device allows to be served as a potentially disposable and sensitive biosensor. (C) 2010 Elsevier B.V. All rights reserved.
Synchrotron Radiation Soft X-ray Induced Reduction in Graphene Oxide Characterized by Time-Resolved Photoelectron Spectroscopy
(2015-06-11)
Lin, Chi-Yuan
;
Cheng, Cheng-En
;
Wang, Shuai
;
Shiu, Hung Wei
;
Chang, Lo Yueh
Synchrotron radiation soft X-ray was employed to reduce graphene oxide (GO) films in ultrahigh vacuum. The dissociation of oxygen-containing functional groups, and the formation of sp(2) C-C bonds were revealed by time-resolved in situ X-ray photoelectron spectroscopy, demonstrating the X-ray reduction of GO. The number of C-O bonds of G-O exhibited an exponential decay with exposure time. The X-ray reduction rate of G-O was positively correlated with the intensity of low-energy secondary electrons excited from substrates by soft X-ray, indicating the C-O bonds were dissociated by secondary electrons.
UV-treated graphene oxide as anode interfacial layers for P3HT: PCBM solar cells
(2015-07-01)
Cheng, Cheng-En
;
Tsai, Cheng-Wei
;
Pei, Zingway
;
Lin, Tsung-Wu
;
Chang, Chen-Shiung
Solution-processable graphene oxide (GO) ultrathin films were introduced as anode interfacial layers (AILs) for polymer solar cells (PSCs). The photovoltaic performance of PSCs containing thermal-and UV-treated GO was comparable to that of PSCs with conventional poly(3,4-ethyledioxythiphene): poly(styrenesulfonate) AILs. UV treatment induced the surface activation of GO; an increase in the work function of UV-treated GO improved the energy band alignment at the GO/poly(3-hexylthiophene) interface, which accounted for the efficient hole collection and photovoltaic performance of PSCs with treated GO.