Browsing by Author "Wu, MF"

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Current-temperature characteristics of low-temperature-sputtered (Ba,Sr)TiO3 films post treated by rapid thermal annealing
(2002)
Shye, DC
;
Chen, JS
;
Kuo, MW
;
Chou, BCS
;
Jan, CK
This work reports the current-temperature characteristics of the low-temperature-sputtered (Ba0.8Sr0.2)TiO3 (BST) film post treated by rapid thermal annealing (RTA) in O-2 ambient. The top electrode was biased under negative/positive voltage to investigate the interface properties of the Pt/BST/Pt multifilm. As the results, the current density of the RTA-treated BST film was greatly reduced owing to compensation of oxygen vacancies. The RTA-treated BST thin film biased at negative voltage exhibits a negative temperature-coefficient-resistivity (NTCR) behavior, but, intriguingly, that biased at positive voltage reveals a positive temperature-coefficient-resistivity (PTCR) behavior. According to the leakage current analysis, the Schottky emission dominates the negative biased current at upper interface, but the Heywang barrier scattering confines the positive biased current.
Dependence of polarization on temperature coefficient resistance of (Ba, Sr)TiO3 thin films post-treated by RTA
(2003-04-01)
Shye, DC
;
Chiou, BS
;
Kuo, MW
;
Chen, JS
;
Chou, BCS
The temperature coefficient of resistance (TCR) characteristics of Pt/(Ba0.8Sr0.2)TiO3 (BST)/Pt thin-film resistors are studied for the BST films with rapid thermal annealing (RTA) treatments. The polarizations induced by bias voltages greatly influence the TCR characteristics. The RTA-treated BST thin film exhibits negative TCR (NTCR) behavior at a negative voltage, but, intriguingly, positive TCR (PTCR) behavior at a positive voltage. According to the leakage current analysis, Schottky emission dominates the negatively biased current at the upper interface, but Heywang barrier scattering confines the positive biased current. (C) 2003 The Electrochemical Society.
New dopant and host materials for blue-light-emitting phosphorescent organic electroluminescent devices
(2005-02-10)
Yeh, SJ
;
Wu, MF
;
Chen, CT
;
Song, YH
;
Chi, Y
Efficient organic light-emitting diodes (OLEDs) incorporating Ir-III bis(4,6-difluorophenylpyridinato)3-(trifluoromethyl)-5-(pyridin-2-yl)-1,2,4-triazolate (FIrtaz) and Ir-III bis(4,6-difluorophenylpyridinato)-5- (pyridin-2-yl)-1H-tetrazolate (FIrN4) demonstrate higher-purity blue-light emission than the long-known Ir-III bis(4,6-difluorophenylpyridinato)-picolate (FIrpic) phosphorophore. New host materials with higher glass-transition temperatures were also found to enhance the OLED performance.
Red fluorenes as the efficient host emitter for non-doped red organic light-emitting diodes
(2005-01-01)
Chiang, CL
;
Wu, MF
;
Shu, CF
;
Chen, CT
;
應用化學系
Crystallinic red fluorophores based on donor-acceptor substituted spirofluorene, i.e., PhSPDCV show strong fluorescence in solution (Phi(f) - 70%) as well as in solid state (Phi(f) > 30 %). Non-doped red OLEDs fabricated with PhSPDCV exhibit authentic red (CIE, x = 0.65, y = 0.35) electroluminescence with brightness over 12,000 cd m(-2) (or > 600 cd m(-2) at 20 mA cm(-2)) and remarkable external quantum efficiency as high as 3.6%. On the other hand, the bis-substituted derivatives of spirofluorene BisPhSPDCV show relatively weak fluorescence both in solution (Phi(f) < 20 %) and in solid state (Phi(f) < 10 %). Although saturated red electroluminescence (CIE, x = 0.65, y = 0.34) is also observed, non-doped red OLED containing BisPhSPDCV performs much worse than PhSPDCV OLEDs. Both PhSPDCV and BisPhSPDCV are not amorphous forming loosely packed crystallinic materials in solid state with no intimate pi-pi interaction.
Thermally driven polysilicon actuators for lateral displacement
(1999-05-01)
Wu, MF
;
Lin, CH
;
Hsu, WS
;
機械工程學系
;
Department of Mechanical Engineering
A novel one-mask; polysilicon actuator driven by thermal expansion is developed, modeled and tested. The structures are heated by electric current due to resistive dissipation. Thermal strain is magnified by two mechanical mechanisms-lever and parallelogram. The device is tested in air and has a lateral 8 mu m-displacement by applying a low voltage (below 3.5 V). The critical current to reach melting point is about 67 mA with the input voltage less than 5 V. The simulation results by analytical and FEM schemes are compared with experimental data. The maximum output forces is measured with a built-in cantilever beam and is calculated to be about 3.3 mu N.