Browsing by Author "Wu, W. F."

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A Comprehensive Kinetical Modeling of Polymorphic Phase Distribution of Ferroelectric-Dielectrics and Interfacial Energy Effects on Negative Capacitance FETs
(2019-01-01)
Tang, Y-T
;
Fang, C-L
;
Kao, Y-C
;
Modolo, N.
;
Su, C-J
This paper clarifies for the first time the origin of ferroelectricity in the Negative Capacitance Field-Effect Transistors (NCFETs) by molecular dynamics (MD) simulation. MD simulation considering atomic interactions between all atoms enables accurate predictions for the microstructure even at all interfaces. By incorporating the results from MD simulations into a kinetic model, it is able to predict the conditions of crystallization and phase transition during RTP and cooling processes that govern ferroelectricity in FETs. Our simulation reveals that the comparable interfacial energy between o- and t- phase, and in-plane tensile stress from metal capping or interfacial layers (ILs) enable more phase transition from t- to o-phase, and more ferroelectricity in NCFETs. Finally, design methodology to maintain the electric variation of NCFETs is also proposed
Influence of oxygen flow rate on photocatalytic TiO2 films deposited by rf magnetron sputtering
(2012-02-01)
Chiou, A. H.
;
Kuo, C. G.
;
Huang, C. H.
;
Wu, W. F.
;
Chou, C. P.
Titanium dioxide (TiO2) thin films having anatase (1 0 1) crystal structure were prepared on non-alkali glass substrates by rf (13.56 MHz) magnetron sputtering using a TiO2 ceramic target under various oxygen partial pressures. At a fixed substrate temperature of 400 A degrees C and total gas pressure of 1 Pa after 3 h deposition. Effects of oxygen partial pressure on the structural, surface morphology, and photocatalytic activities of the TiO2 thin films were investigated. We performed both photoinduced decomposition of methylene blue (MB) and photoinduced hydrophilicity under UV light illumination. The XRD patterns exhibited a broad-hump shape indicating the amorphous structure of TiO2 thin films. The results showed that when the [O-2/(Ar + O-2)] flow rate increased to 50%, the photoinduced decomposition of MB and photoinduced hydrophilicity were enhanced. The water contact angle after 9 min UV illumination was approximately 4.5A degrees, and the methylene blue (MB) solution decomposition from 12 down to 3.34 mu mol/L for 240 min UV irradiation.