Browsing by Author "Wu, TB"

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Mechanism for slow switching effect in advanced low-voltage, high-speed Pb(Zr1-XTiX)O-3 ferroelectric memory
(2005-06-01)
Tsai, CW
;
Lai, SC
;
Yen, CT
;
Lien, HM
;
Lung, HL
Slow-switching effect in PZT ferroelectric memory under low-voltage and high-speed operation is observed. The slow-switching effect becomes worse at lower operation voltage and elevated temperature. This effect significantly reduces the sensing margin and causes severe reliability issue for advanced ferroelectric memory, particularly for low-voltage and high-speed applications. This slow-switching effect is believed to be attributed to slowing down of polarization switching caused by band bending from Schottky built-in potential at the electrode/ferroelectric interface. The proposed mechanism is supported by the polarity dependence in an asymmetric LNO/PZT/Pt sample.
Microstructures and electrical properties of V2O5-based multicomponent ZnO varistors prepared by microwave sintering process
(1997-03-01)
Chen, CS
;
Kuo, CT
;
Wu, TB
;
Lin, IN
;
材料科學與工程學系
The V2O5-based ZnO varistor materials were successfully densified using microwave sintering process. The materials can reach a high density as 94.6% T.D. (theoretical density) when sintered at 800 degrees C (10 min) but the grain growth was initiated only when sintered at a higher temperature than 1000 degrees C (10 min). The varistor characteristics, including breakdown voltage (V-bk), nonlinear coefficient (alpha) and leakage current density (J(L)), degraded markedly for the samples sintered at too high temperature (i.e., T greater than or equal to 1000 degrees C) and for too long period (i.e., t greater than or equal to 10 min) that was ascribed to the occurrence of abnormal grain growth. Contrarily, the intrinsic characteristics, including potential barrier height (phi(b)) and donor density (N-d), varied only moderately with these sintering conditions. The V2O5-based ZnO materials sintered at 1000 degrees C (5 min) possessed good varistor characteristics as V-bk = 248 V/mm, alpha = 31 and J(L) = 4.6 x 10(-5) A/cm(2). The corresponding intrinsic parameters are phi(b) = 0.63 eV and N-d = 2.37 x 10(24) m(-3).
Microstructures and electrical properties of V2O5-based multicomponent ZnO varistors prepared by microwave sintering process
(1997-03-01)
Chen, CS
;
Kuo, CT
;
Wu, TB
;
Lin, IN
;
材料科學與工程學系
The V2O5-based ZnO varistor materials were successfully densified using microwave sintering process. The materials can reach a high density as 94.6% T.D. (theoretical density) when sintered at 800 degrees C (10 min) but the grain growth was initiated only when sintered at a higher temperature than 1000 degrees C (10 min). The varistor characteristics, including breakdown voltage (V-bk), nonlinear coefficient (alpha) and leakage current density (J(L)), degraded markedly for the samples sintered at too high temperature (i.e., T greater than or equal to 1000 degrees C) and for too long period (i.e., t greater than or equal to 10 min) that was ascribed to the occurrence of abnormal grain growth. Contrarily, the intrinsic characteristics, including potential barrier height (phi(b)) and donor density (N-d), varied only moderately with these sintering conditions. The V2O5-based ZnO materials sintered at 1000 degrees C (5 min) possessed good varistor characteristics as V-bk = 248 V/mm, alpha = 31 and J(L) = 4.6 x 10(-5) A/cm(2). The corresponding intrinsic parameters are phi(b) = 0.63 eV and N-d = 2.37 x 10(24) m(-3).