Browsing by Author "Chiu, KC"

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Formulas for computing the magnetic flux density of fine magnetic pole pitch fabricated on printed circuit board
(2005-04-01)
Chiu, KC
;
Huang, DR
;
Shieh, HPD
;
光電工程學系
;
Department of Photonics
A special wire circuit with an appropriate layout was designed and formed on printed circuit board (PCB). After a current flowed through the wire circuit, the magnetic field was induced according to Ampere's law and a fine magnetic pole pitch of less than 1 mm was fabricated. Three-dimensional formulas are presented for computing the magnetic flux density of fine magnetic pole pitch fabricated on PCB. These formulas are expressed in terms of finite sums of elementary functions and enable rapid parametric studies of the magnetic flux density distribution relative to wire width, wire thickness, dimension of magnetic pole pitch, etc. They are easily programmed and have been successfully verified by experimental measurements. © 2004 Elsevier B.V. All rights reserved.
Low cogging torque and high efficient 3-phase spindle motors by reshaping magnetic circuit profiles
(2001-07-01)
Chiu, KC
;
Huang, DR
;
Shieh, HPD
;
光電工程學系
;
Department of Photonics
The dynamic characteristics of a 3-phase spindle motor with 12-poles and 9-slots can be improved by reshaping the magnetic circuit profiles. The stator cores were designed with different ratios of x/y where x is the gap angle between 2-slots and y is the expanded angle of a slot. Experiment and finite element analyses (FEA) results show that x/y ratio of 1/2.5 is an optimal design in achieving dynamic performance for DVD drives applications.
Optical characterization of ZnSe epilayers and ZnCdSe/ZnSe quantum wells grown on Ge/Ge0.95Si0.05/Ge0.9Si0.1/Si virtual substrates
(2006-03-15)
Ku, JT
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Kuo, MC
;
Shen, JL
;
Chiu, KC
;
Yang, TH
Several approaches have been employed to grow high-quality ZnSe epilayers on Ge/Ge0.95Si0.05/Ge0.9Si0.1/Si virtual substrates. The ZnSe epilayers were characterized by photoluminescence spectroscopy. Migration enhanced epitaxy and inserting an in situ thermal annealing ZnSe buffer layer effectively reduced the intensity of deep level emissions from the ZnSe epilayer grown on a 6 degrees-tilted Ge/Ge0.95Si0.05/Ge0.9Si0.1/Si virtual substrate. Optimized conditions for growing high-quality ZnSe were used to deposit ZnCdSe/ZnSe multiple quantum wells on Ge/Ge0.95Si0.05/Ge0.9Si0.1/Si virtual substrates. Photoluminescence spectroscopy revealed quantum-confinement effect in the ZnCdSe multiple quantum wells. The evolution of the exciton emission peak energy and the linewidth as a function of temperature indicate a low density of localized sites in the sample with a well width of 1 nm. In the high-temperature regime, the thermal quenching of the excitonic emission intensity from ZnCdSe quantum well structures was governed by the thermal activation of carriers from quantum-well-confined states into barrier states. (c) 2006 American Institute of Physics.
Optical properties of Zn1-xCdxSe epilayers grown on (100)GaAs by molecular beam epitaxy
(2004-08-01)
Kuo, MC
;
Chiu, KC
;
Shih, TH
;
Lai, YJ
;
Yang, CS
Zn1-xCdxSe epilayers were grown on (100) GaAs substrates by molecular beam epitaxy. Lattice constants of the epilayers were measured by (004) rocking curve X-ray diffraction. A full width at half maximum of 475 to 2100 arcsec was obtained. The dependence of the energy gap on temperature, measured by the photoluminescence (PL) spectra, was fitted by Varshni's [Y. P. Varshni: Physica 34 149 (1967)] and O'Donnell's [R. P. O'Donnell and X. Chen: Appl. Phys. Lett. 58 2924 (1991)] models. The fitting parameters beta (161 K to 368K) and (hv) (13 meV to 24 meV), related to phonon energy, were obtained from Varshni and O'Donnell fits, respectively. The activation energies calculated from the integrated PL intensity versus inverse temperature decrease as the Cd content increases. The broadening of the PL linewidth with temperature was fitted by Gamma(T) = Gamma(0) + Gamma(a)T + Gamma(LOI)/[exp(homega(LOI)/kT) - 1] + Gamma(LO2)/[exp(homega(LO2)/kT) - 1] + Gamma(i)exp(-/kT). The impurity binding energy, (E-b), was found to decrease as the Cd composition increases.
Optical properties of Zn1-xMnxSe epilayers grown by molecular beam epitaxy
(1998-04-01)
Chou, WC
;
Ro, CS
;
Hong, DY
;
Yang, CS
;
Lin, CY
Zn1-xMnxSe (x less than or equal to 0.78) epilayers were grown on the GaAs (001) substrate with tilt angle 0, 3, 10, and 15 degrees toward [010] by the molecular beam epitaxy. The reflectivity, transmission, and photoluminescence experiments were used to measure the energy gap of the epilayers. A red shift of 4 meV was found as the substrate tilt angle increased from 0 to 15 degrees. The red shift in band gap energy is attributed to the increasing incoporation of smaller Zn ion with the increase in the kink density which results from the increase in the substrate tilt angle. In addition, the lattice vibration of the Zn1-xMnxSe (0 less than or equal to x less than or equal to 0.78) epilayers measured by the Raman scattering was found to follow the intermediate mode behavior of type Ib instead of type Ic. The force constants F-MnSe = 2.81 x 10(6) amu.cm(-2) and F-ZnSe = 3.96 x 10(6) amu.cm(-2) were obtained.
Optimal design of fine magnetic pole pitch fabricated on printed circuit board
(2005-05-15)
Chiu, KC
;
Huang, DR
;
Shieh, HPD
;
光電工程學系
;
Department of Photonics
Using traditional methods, a permanent magnet multipole component magnetized with a magnetic pole pitch of less than 1 mm is very difficult to achieve and a costly, complicated magnetization system is required. In this paper, the optimal design of a fine magnetic pole pitch of less than 1 mm fabricated on a printed circuit board has been successfully investigated and demonstrated. An optimal magnetic pole pitch having large variation and strength in magnetic-flux density was obtained. The characteristics of the optimal magnetic pole pitch are good for signal detection and processing. The measured values of the magnetic-flux density in the z component are in agreement with the calculated values. (c) 2005 American Institute of Physics.