Browsing by Author "Tang, J."

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Effective surface treatments for selective epitaxial SiGe growth in locally strained pMOSFETs
(2007-01-01)
Cheng, P. L.
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Liao, C. I.
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Wu, H. R.
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Chen, Y. C.
;
Chien, C. C.
Several dry and wet surface treatment methods are explored for a selective SiGe epitaxial film used to fabricate embedded SiGe pMOSFETs. Pre-clean conditions for the device wafers used in this study were limited by a realistic CMOS process window with tight thermal and chemical budgets due to dopant diffusion and hardmask erosion concerns. The effectiveness of these pre-clean methods is evaluated by SiGe epitaxial film quality and SIMS profiles of key residual contaminants such as C and O at the SiGe-Si substrate interface. As an effective low-temperature dry surface treatment, chemical bake in HCl/H-2 at temperature below 800 degrees C is found to reduce interface C and O peak concentrations by an order of magnitude. Wet clean in multiple cycles of DIW-O-3 (ozonated water), SC1 and diluted HF (DHF) is also presented to prepare epitaxial growth surfaces with accumulated damage and chemical residues from previous process steps. SiGe epitaxial film morphology is also observed to improve by increasing DHF clean time. For further improvement of film quality on the most difficult surfaces, Si seed layer was employed to initiate SiGe film nucleation and yield smooth film growth.
Fabrication and characterization of double-wall carbon nanotube absorber for passive mode-locked Nd:GdVO(4) laser
(2011-10-01)
Wang, Y. G.
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Qu, Z. S.
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Liu, J.
;
Tang, J.
;
光電工程學系
Using the vertical evaporation technique we fabricated saturable absorbers by transferring the double-wall carbon nanotubes (DWCNT) onto a hydrophilic quartz substrate. The fast recovery time and the saturation intensity of the absorber were measured to be 228 fs and 130 mu J/cm(2), respectively, at 1060 nm. The modulation depth of the absorber was about 3.7%. Passive mode-locked Nd:GdVO(4) laser was demonstrated. The continuous wave mode-locked pulses pulse duration is 5.6 ps and the largest average output power is 1.2 W at the pump power of 9.5 W. To the best of our knowledge, this is the first demonstration of high power continuous wave mode locking laser with DWCNT absorber.
Fabrication and characterization of double-wall carbon nanotube absorber for passive mode-locked Nd:GdVO4 laser
(2011-10-01)
Wang, Y. G.
;
Qu, Z. S.
;
Liu, J.
;
Tang, J.
;
光電工程學系
Using the vertical evaporation technique we fabricated saturable absorbers by transferring the double-wall carbon nanotubes (DWCNT) onto a hydrophilic quartz substrate. The fast recovery time and the saturation intensity of the absorber were measured to be 228 fs and 130 mu J/cm(2), respectively, at 1060 nm. The modulation depth of the absorber was about 3.7%. Passive mode-locked Nd:GdVO4 laser was demonstrated. The continuous wave mode-locked pulses pulse duration is 5.6 ps and the largest average output power is 1.2 W at the pump power of 9.5 W. To the best of our knowledge, this is the first demonstration of high power continuous wave mode locking laser with DWCNT absorber.
Fabrication of aligned single wall carbon nanotube absorbers for high power passive mode-locked Nd:GdVO(4) laser
(2012-01-01)
Cheng, S. Y.
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Wang, Y. G.
;
Yu, P.
;
Cheng, Y. J.
;
Tang, J.
Using the vertical evaporation technique we fabricated saturable absorbers by transferring the water-soluble single wall carbon nanotubes (SWCNT) onto a hydrophilic quartz substrate. The fast recovery times of the absorber were measured to be 136 and 790 fs. The modulation depth of the absorber was about 2%. Passive mode-locked Nd:GdVO(4) laser using such an absorber was demonstrated. The continuous wave mode-locked pulses with the pulse duration of 12.4 ps and the repetition of 120 MHz were achieved. The maximum average output power of the mode-locked laser is 2.4 W at the pump power of 13 W. Such kind of absorber has potential to be put into practical use for high power solid-state laser mode locking.
Fabrication of aligned single wall carbon nanotube absorbers for high power passive mode-locked Nd:GdVO4 laser
(2012-01-01)
Cheng, S. Y.
;
Wang, Y. G.
;
Yu, P.
;
Cheng, Y. J.
;
Tang, J.
Using the vertical evaporation technique we fabricated saturable absorbers by transferring the water-soluble single wall carbon nanotubes (SWCNT) onto a hydrophilic quartz substrate. The fast recovery times of the absorber were measured to be 136 and 790 fs. The modulation depth of the absorber was about 2%. Passive mode-locked Nd:GdVO4 laser using such an absorber was demonstrated. The continuous wave mode-locked pulses with the pulse duration of 12.4 ps and the repetition of 120 MHz were achieved. The maximum average output power of the mode-locked laser is 2.4 W at the pump power of 13 W. Such kind of absorber has potential to be put into practical use for high power solid-state laser mode locking.
Saturable absorber at 940 nm using single wall carbon nanotubes deposited by vertical evaporation technique
(2012)
Wang, Y. G.
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Cheng, S. Y.
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Tai, P. T.
;
Tang, J.
;
光電工程學系
The vertical evaporation technique allows us to fabricate aligned single wall carbon saturable absorbers. The nonlinear parameters of the absorber at the wavelength of 940 nm were measured. The measured bi-exponential lifetimes of the absorber are 330 fs and 850 fs, respectively. The saturation intensity and modulation depth were found to be 2000 mu J/cm(2) and 10% for SWCNT absorber at the direction of alignment, in comparison to 950 mu J/cm(2) and 7% for the SWCNT solution. Crown Copyright (C) 2011 Published by Elsevier GmbH. All rights reserved.
Single fluorescent gold nanoclusters
(2009-08-31)
Yuan, C. T.
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Chou, W. C.
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Tang, J.
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Lin, C. A.
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Chang, W. H.
Both ensemble and single-molecule measurements were performed to explore the fluorescence properties of Au nanoclusters (NCs). Photoinduced fluorescence enhancement was observed for ensemble NCs in solution, but photobleaching was found at ambient environments. At the single-molecule level, fluorescence blinking and single-step photobleaching were observed. Furthermore, their time-resolved fluorescence shows a single exponential decay with a lifetime of similar to 7 ns and is insensitive to changes in fluorescence intensity. The lifetime distribution is more homogeneous within ensemble Au NCs as compared to CdSe QDs. Therefore, Au NCs have potential applications as nontoxic fluorescent labels for lifetime-based imaging microscopy. However, their low quantum yields and poor photostability are disadvantageous factors, which require further improvement. (C) 2009 Optical Society of America