Browsing by Author "Shiu, Hung Wei"

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Graphene On Au-Coated SiOx Substrate: Its Core-Level Photoelectron Microspectroscopy Study
(2012-08-01)
Chen, Jhih-Wei
;
Wang, Chiang-Lun
;
Shiu, Hung Wei
;
Lin, Chi-Yuan
;
Chang, Chen-Shiung
"The core-level electronic structures of exfoliated graphene sheets on a Au-coated SiOx substrate have been studied using synchrotron radiation photoelectron spectroscopy (SR-PES) on a micron scale. The graphene's visibility on the Au-coated SiOx substrate was first demonstrated by micro optical characterization, and then an SR-PES study was conducted. Because of the elimination of charging effect, a precise C 1s core-level characterization shows graphitic and contaminated carbon states of graphene. Different levels of Au-coating-induced p-type doping on single-and double-layer graphene sheets were also examined in the C 1s core-level shift. The Au-coated SiOx substrate can be treated as a simple but high-throughput platform for in situ studying graphene under further hybridization by PES. (C) 2012 The Japan Society of Applied Physics"
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.