Browsing by Author "Lee, Yen-Chih"

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Electron field emission properties on UNCD coated Si-nanowires
(2008-04-01)
Tzeng, Yu-Fen
;
Lee, Yen-Chih
;
Lee, Chi-Young
;
Chiu, Hsin-Tien
;
Lin, I-Nan
The electron field emission (EFE) properties of Si-nanowires (SiNW) were improved by coating a UNCD films on the SiNWs. The SiNWs were synthesized by an electroless metal deposition (EMD) process, whereas the UNCD films were deposited directly on bare SiNW templates using Ar-plasma based microwave plasma enhanced chemical vapor deposition (MPE-CVD) process. The electron field emission properties of thus made nano-emitters increase with MPE-CVD time interval for coating the UNCD films, attaining small turn-on field (E(0)=6.4 V/mu m) and large emission current density (J(e)=6.0 mA/cm(2) at 12.6 V/mu m). This is presumably owing to the higher UNCD granulation density and better UNCD-to-Si electrical contact on SiNWs. The electron field emission behavior of these UNCD nanowires emitters is significantly better than the bare SiNW ((E(0))(SiNWs)=8.6 V/mu m and (J(e))(SiNWs)<0.01 mA/cm(2) at the same applied field) and is comparable to those for carbon nanotubes. (C) 2008 Elsevier B.V. All rights reserved.
Fabrication of an ultra-nanocrystalline diamond-coated silicon wire array with enhanced field-emission performance
(2007-10-31)
Tzeng, Yu-Fen
;
Liu, Kao-Hsiang
;
Lee, Yen-Chih
;
Lin, Sue-Jian
;
Lin, I-Nan
Large- area ultra- nanocrystalline diamond- coated silicon nanowire ( UNCD/ SiNW) field- emitter arrays were prepared by the deposition of ultra- nanocrystalline diamond ( UNCD) on the tips of arrays of silicon nanowires ( SiNWs) with uniform diameters. The electron field- emission ( EFE) behavior of UNCD/ SiNW arrays as well as that of the SiNW arrays has been observed. The SiNWs exhibit good electron field- emission properties with turn- on fields ( E0) of about 7.6 V mu m- 1, which is superior to the EFE properties of planar- silicon materials. The turn- on fields are related to the diameter of the SiNWs. Coating the SiNWs with a UNCD film further improves their EFE properties. The threshold field for attaining J(e) = 0.1 mAcm(-2) EFE current density is 16.0 V mu m(-1) for bare SiNWs and 10.2 V mu m(-1) for UNCD/ SiNWs. The improvement in EFE properties due to the UNCD coating is presumably due to the lower work function of field emission of the UNCD materials, compared to that of the silicon materials.
On the enhancement of field emission performance of ultrananocrystalline diamond coated nanoemitters
(2007-08-06)
Tzeng, Yu-Fen
;
Lee, Yen-Chih
;
Lee, Chi-Young
;
Lin, I.-Nan
;
Chiu, Hsin-Tien
Ultrananocrystalline diamond (UNCD) nanoemitters were synthesized by a microwave plasma enhanced chemical vapor deposition process using silicon nanowires (SiNWs) as the template. Preseeding markedly enhances the nucleation of diamond on the SiNW templates, resulting in UNCD grains of smaller size and uniform distribution, which leads to significantly improved electron field emission (EFE) properties. The EFE for UNCD nanoemitters can be turned on at (E(0))(UNCD-NE)=4.4 V/mu m, achieving large EFE current density, (J(e))(UNCD-NE)=13.9 mA/cm(2) at an applied field of 12 V/mu m, which is comparable with that of carbon nanotubes, but with much better processing reliability. (c) 2007 American Institute of Physics.