Browsing by Author "Lin, Yu-Chuan"

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Efficient reduction of graphene oxide catalyzed by copper
(2012)
Lin, Yu-Chuan
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Liu, Keng-Ku
;
Wu, Chih-Yu
;
Chu, Chih-Wei
;
Wang, Jacob Tse-Wei
We report that copper thin films deposited on top of graphene oxide (GO) serve as an effective catalyst to reduce GO sheets in a diluted hydrogen environment at high temperature. The reduced GO (rGO) sheets exhibit higher effective field-effect hole mobility, up to 80 cm(2) V-1 s(-1), and lower sheet resistance (13 k Omega square(-1)) compared with those reduced by reported methods such as hydrazine and thermal annealing. Raman and XPS characterizations are addressed to study the reduction mechanism on graphene oxide underneath copper thin films. The level of reduction in rGO sheets is examined by Raman spectroscopy and it is well correlated with hole mobility values. The conductivity enhancement is attributed to the growth of the graphitic domain size. This method is not only suitable for reduction of single GO sheets but also applicable to lower the sheet resistance of Langmuir-Blodgett assembled GO films.
Growth of Large-Area and Highly Crystalline MoS2 Thin Layers on Insulating Substrates
(2012-03-01)
Liu, Keng-Ku
;
Zhang, Wenjing
;
Lee, Yi-Hsien
;
Lin, Yu-Chuan
;
Chang, Mu-Tung
The two-dimensional layer of molybdenum disulfide (MoS2) has recently attracted much interest due to its direct-gap property and potential applications in optoelectronics and energy harvesting. However, the synthetic approach to obtain high-quality and large-area MoS2 atomic thin layers is still rare. Here we report that the high-temperature annealing of a thermally decomposed ammonium thiomolybdate layer in the presence of sulfur can produce large-area MoS2 thin layers with superior electrical performance on insulating substrates. Spectroscopic and microscopic results reveal that the synthesized MoS2 sheets are highly crystalline. The electron mobility of the bottom-gate transistor devices made of the synthesized MoS2 layer is comparable with those of the micromechanically exfoliated thin sheets from MoS2 crystals. This synthetic approach is simple, scalable, and applicable to other transition metal dichalcogenides. Meanwhile, the obtained MoS2 films are transferable to arbitrary substrates, providing great opportunities to make layered composites by stacking various atomically thin layers.
Solvent-less Repair Inks for Color Filters
(2011)
Chen, Huang-Ming Philip
;
Tang, Feng-Chin
;
Li, Chi-Hsin
;
Hsieh, Wen-Jen
;
Lin, Yu-Chuan
Color filter (CF), one of the key components for liquid crystal display (LCD), is costly to make from repeated lithography processes. The defects may be created during the repeated lithography processes. The recycling defect CF panels are environmental unfriendly and not cost-effective process. CF repairing is an important cost-effective technical process to improve product yield. In this study, a solvent-less repaired ink system was studied. The optimized formulas of red, green, blue, and black inks have passed the quality control, reliability, and life-time tests. The new solvent-free ink system possesses the balance characteristics in liquid fluidic, UV reactivity, and color saturation. The energy has been conserved without high temperature process for removing organic solvent. The new system exhibits the state-of-the-art fabrication process without unnecessary energy waste. As a result, the solvent-less CF repair inks offer a promising result for contributing to a low carbon process in the near future.
Wafer-scale MoS2 thin layers prepared by MoO3 sulfurization
(2012)
Lin, Yu-Chuan
;
Zhang, Wenjing
;
Huang, Jing-Kai
;
Liu, Keng-Ku
;
Lee, Yi-Hsien
Atomically thin molybdenum disulfide (MoS2) layers have attracted great interest due to their direct-gap property and potential applications in optoelectronics and energy harvesting. Meanwhile, they are extremely bendable, promising for applications in flexible electronics. However, the synthetic approach to obtain large-area MoS2 atomic thin layers is still lacking. Here we report that wafer-scale MoS2 thin layers can be obtained using MoO3 thin films as a starting material followed by a two-step thermal process, reduction of MoO3 at 500 degrees C in hydrogen and sulfurization at 1000 degrees C in the presence of sulfur. Spectroscopic, optical and electrical characterizations reveal that these films are polycrystalline and with semiconductor properties. The obtained MoS2 films are uniform in thickness and easily transferable to arbitrary substrates, which make such films suitable for flexible electronics or optoelectronics.