Browsing by Author "Chen, Kai-Ling"

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Highly graphitized laterally interconnected SWCNT network synthesis via a sandwich-grown method
(2011-04-13)
Teng, I-Ju
;
Chen, Kai-Ling
;
Hsu, Hui-Lin
;
Jian, Sheng-Rui
;
Wang, Li-Chun
We present a sandwich-grown method for growing laterally interconnected single-walled carbon nanotube (SWCNT) networks with a high degree of graphitization by microwave plasma chemical vapour deposition (MPCVD). An Al(2)O(3)-supported Fe catalyst precursor layer deposited on an oxidized Si substrate with an upper Si cover is first pretreated in pure hydrogen, and then exposed to a gas mixture of methane/hydrogen for growth process at a lower growth temperature and a faster rate. The effects of various parameters, such as catalyst film thickness, gas flow rate, working pressure, growth time and plasma power, on the morphologies and structural characteristics of the SWCNT networks are investigated, and therefore provide the essential conditions for direct growth of laterally interconnected SWCNT networks. Analytical results demonstrate that the SWCNT-based lateral architecture comprises a mixture of graphene-sheet-wrapped catalyst particles and laterally interconnected nanotubes, isolated or branched or assembled into bundles. The results also show that the formation of the laterally interconnected SWCNT networks is related to the sandwich-like stack approach and the addition of an Al(2)O(3) layer in the MPCVD process. The successful growth of lateral SWCNT networks provides new experimental information for simply and efficiently preparing lateral SWCNTs on unpatterned substrates, and opens a pathway to create network-structured nanotube-based devices.
Temperature-dependent electrical and photo-sensing properties of horizontally-oriented carbon nanotube networks synthesized by sandwich-growth microwave plasma chemical vapor deposition
(2013-02-01)
Teng, I-Ju
;
Hsu, Hui-Lin
;
Jian, Sheng-Rui
;
Wang, Li-Chun
;
Chen, Kai-Ling
The electrical and photo-sensing properties of horizontally-oriented interconnected carbon nanotube networks (CNT-NWs) prepared by means of a microwave plasma chemical vapor deposition sandwich-growth process are investigated. The temperature-dependent dark and illuminated current-voltage and transfer characteristics of CNT-NW-assisted devices are measured. Results show that the current-voltage characteristics of the devices exhibit nonlinear behavior, and the current can be further modulated by a gate voltage, revealing p-type semiconducting behavior with a device mobility of similar to 14.5 cm(2)/V.s and an on-off current ratio of -10(3). Moreover, when the CNT-NW-assisted devices are irradiated with 1.25-25 mu m infrared (IR) from 300 to 11 K, the photo currents increase approximately 1.1- to 2.7-fold compared to the dark currents at +/- 2 V bias voltage. Such results demonstrate that the presented CNT-NWs have high potential for IR photo-sensor applications. (C) 2012 Elsevier B.V. All rights reserved.