Browsing by Author "Sheng, Pei-Sun"

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Deposition of mesoporous silicon carbide thin films from (Me3Si)(4)Sn: Tin nanoparticles as in situ generated templates
(2007-10-30)
Wang, Chia-Hsin
;
Shen, Wen-Yih
;
Sheng, Pei-Sun
;
Lee, Chi-Young
;
Chiu, Hsin-Tien
With use of Sn(SiMe3)(4) as the precursor, amorphous SiC1+x thin films with Sri nanoparticles embedded were grown on Si substrates at 923 K by low-pressure chemical vapor deposition. After treatment under hydrogen plasma at 923 K, the Sri nanoparticles in the films were removed by an HF solution and by evaporation at 1423 K. Following the removal of Sri, high-temperature treatments at 1273-1423 K converted the amorphous thin films into mesoporous semiconducting beta-SiC thin films with pore sizes 10-100 nm.
Preparation of Mo2C@a-C core-shell powders via carburization of Mo particles by 1-chlorobutane and hexachlorobenzene
(2007-07-01)
Chien, Chun-Hsiung
;
Sheng, Pei-Sun
;
Wang, Chia-Hsin
;
Huang, Chih-Hao
;
Lin, Huang-Kai
Mo2C@a-C core-shell powders were prepared by reacting Mo powders with gaseous 1-chlorobutane or hexachlorobenzene at 1173 K. The chlorinated reactants acted as the source of carbon for the carburization of Mo and the source of chlorine, which assists the etching of Mo to reduced particle sizes. (C) 2006 Elsevier B.V. All rights reserved.
Stacked Silicon Nanowires with Improved Field Enhancement Factor
(2010-02-01)
Tzeng, Yu-Fen
;
Wu, Hung-Chi
;
Sheng, Pei-Sun
;
Tai, Nyan-Hwa
;
Chiu, Hsin Tien
This work describes newly structured stacked silicon nanowires (s-SiNWs), consisting of nanosized silicon wires on top of silicon microrods (SiMRs) and exhibiting pronouncedly superior electron held emission (EFE) characteristics to the conventional SiNWs, by using a two-step electroless metal deposition process. Experimental results indicate that for these s-SiNWs, the electrostatic "screen effect" is markedly suppressed and the held enhancement factor (beta-value) is significantly increased ((beta)(s-SiNWs) = 2533). Additionally, the turn-on held (Eo) for triggering the EFE process is reduced to a level comparable with that of carbon nanotubes, viz. (E(0))(s-SiNWs) = 2.0 V/mu m. This simple and robust modified electroless metal deposition approach does not require either a high temperature or an expensive photolithographic process and possesses great potential for applications.
Synthesis of carbon hollow spheres and particles from CCl4 and Mo
(2008-03-31)
Chien, Chun-Hsiung
;
Sheng, Pei-Sun
;
Wang, Chia-Hsi
;
Huang, Chi-Hao
;
Lin, Huang-Kai
Carbon materials with different morphology were prepared by reacting CCl4 and Mo at 873-1173 K. At 873-973 K, hollow spheres (diameter: 1-3 mu m, shell thickness: 50 nm) were obtained. At 1073 K, particles (diameter: 50-100 nm) encapsulated in spherical shells (diameter: 1-5 mu m) were collected. At H 73 K, formation of particles (diameter: 200-300 nm) was observed. Mo acted as a reagent to remove chlorine atoms from the carbon source and a template for the formation of the spherical structures. We propose that reaction temperature and polymerization of chlorinated species formed from the pyrolysis of CCl4 affect the morphology of carbon products greatly. (C) 2007 Elsevier B.V. All rights reserved.