Browsing by Author "Lee, Trent Gwo-Yann"

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Characteristics of low-temperature pulse-laser-deposited (Pb,Sr)TiO3 films in metal/ferroelectric/silicon structure
(2007-01-07)
Wang, Jyh-Liang
;
Lai, Yi-Sheng
;
Lee, Trent Gwo-Yann
;
Chiou, Bi-Shiou
;
Tsai, Chun-Chien
In this study, pulsed- laser deposited ( Pb, Sr) TiO3 ( PSrT) films on p- type Si were studied at low substrate temperatures ranging from 300 to 450 degrees C for metal/ ferroelectric/ semiconductor applications. The substrate temperature strongly enhances film crystallinity without significant inter- diffusion at the PSrT/ Si interface and affects the electrical properties. As the substrate temperature increases, the films have smaller leakage currents, fewer trap states at the electrode interfaces, clockwise capacitance versus applied field hysteresis loops and larger memory windows correlated with superior crystallinity. Conversely, 300 degrees C- deposited films exhibit a small and counterclockwise loop with a positive shift of the flatband voltage, attributed to more negative trap charges within the films. However, the high substrate temperature ( 450 degrees C) may produce serious Pb - O volatilization, incurring more defects and leakage degradation. The analyses of fixed charge density and flatband voltage shift reveal the trap status and agree well with the leakage characteristic. An electron band model of the Pt/ PSrT/ Si electronic structure is proposed to explain the electrical behaviour. The excellent fatigue endurance with a small variation of memory windows (< 11%) after 1010 switching is also demonstrated.
Temperature-dependent characteristics of pulse-laser-deposited (Pb,Sr)TiO3 films at low temperatures
(2008-01-01)
Wang, Jyh-Liang
;
Lai, Yi-Sheng
;
Chiou, Bi-Shiou
;
Chou, Chen-Chia
;
Lee, Trent Gwo-Yann
Pulsed laser deposition (PLD) of (Pb,Sr)TiO3 (PSrT) film on Pt/SiO2/Si at low substrate temperatures (T-s), ranging from 300-450 degrees C, has been investigated. As T-s increases, the films reveal coarsening clusters, improved crystallization of the perovskite phase, distinct capacitance-electric field (C-E) hysteretic loops and a larger dielectric constant. The 350 degrees C-deposited film shows strong (100) preferred orientation and optimum dielectric properties with the dielectric constant of similar to 620. The current density increases as the measurement temperature and the electric field increase. Moreover, PSrT films exhibit a strong negative temperature coefficient of resistance (NTCR) behavior at temperatures ranging from 100 to 390 degrees C.