Browsing by Author "Yu, J. -P."

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Modeling of the integrated magnetic focusing and gated field-emission device with single carbon nanotube
(2007-01-01)
Chen, P. -Y.
;
Hsu, K. -H.
;
Cheng, K. -W.
;
Hung, C. -T
;
Wu, J. -S.
A gated single carbon nanotube field emitter with magnetic focusing is proposed and simulated using a parallelized Poisson's equation solver, coupled with the ray tracing of electrons, on an unstructured tetrahedral adaptive mesh. The magnetic focusing for the electrons can be achieved by a vertically downward magnetic focusing field (-B-z) through the use of either external solenoids or permanent magnets around the field-emission array. The simulation results, assuming uniform magnetic field inside a field-emission unit, are compared with those conventional tetrode-type field emitters using an electrostatic focusing structure. The results reveal that the magnetic focusing design can promise much higher emission current, while a much smaller spot size results at the anode. In addition, the magnitude of the applied gate voltage in the range of 60-120 V shows little influence on the electron-beam diameter at the anode. The proposed magnetic focusing method can also possibly reduce the complexity of the fabrication without the electrostatic focusing structure. Noticeably, a distribution, similar to the Airy function, is obtained that shows the dependence of the spot size at the anode on the magnetic flux intensity. Thus, under suitable magnetic focusing conditions, it is possible to produce well-defined microelectron sources for many field-emission applications, such as novel parallel electron-beam lithography or field-emission displays. (c) 2007 American Vacuum Society.
Numerical Investigation of a Parallel-Plate Atmospheric-Pressure Nitrogen/Ammonia Dielectric Barrier Discharge
(2012-06-01)
Li, F. -L.
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Lin, K. -M.
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Yang, Y. -W.
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Hung, C. -T.
;
Wu, J. -S.
In this paper, a planar atmospheric-pressure dielectric barrier discharge (AP-DBD) of nitrogen mixed with ammonia (0-2 %) is simulated using one-dimensional self-consistent fluid modeling with cell-centered finite-volume method. This AP-DBD is driven by a 30 kHz power source with distorted sinusoidal voltages. The simulated discharge current densities are found to be in good agreement with the experiment data in both phase and magnitude. The simulated results show that the discharges of N-2 mixed with NH3 (0-2 %) are all typical Townsend-like discharges because the ions always outnumber the electrons very much which leads to no quasi-neutral region in the gap throughout the cycle. N-2 (+) and N-4 (+) are found to be the most abundant charged species during and after the breakdown process, respectively, like a pure nitrogen DBD. NH4 (+) increases rapidly initially with increasing addition of NH3 and levels off eventually. In addition, N is the most dominant neutral species, except the background species, N-2 and NH3, and NH2 and H are the second dominant species, which increase with increasing added NH3. The existence of abundant NH2 plays an important role in those applications which require functional group incorporation.
Three-dimensional simulation studies on electrostatic predictions for carbon nanotube field effect transistors (vol 177, pg 683, 2007)
(2008-05-15)
Chen, P. -Y.
;
Shao, Y. -L.
;
Cheng, K. -W.
;
Hsu, K. -H.
;
Wu, J. -S.