Browsing by Author "Chou, HY"

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Dielectric and electrical properties of SrTiO(3+/-y)-(SiO2)(x) thin films
(2005-07-21)
Chou, HY
;
Chen, TM
;
Tseng, TY
;
應用化學系
;
電子工程學系及電子研究所
110 nm thick SrTiO(3 +/- y)-(SiO2), thin films with x = 0-0.45 were prepared on Pt/Ti/SiO2/Si substrates using the chemical solution deposition method and then annealed at temperatures ranging from 600 degrees C to 900 degrees C for I min. The dielectric and electrical properties of the SrTiO(3 +/- y)-(SiO2)(x) were obviously affected by the annealing temperature and composition. The dielectric constant of the thin films increased with increasing annealing temperature and decreased with an increase in Si content while the leakage current density decreased with an increase in Si content. The 700 degrees C annealed SrTiO(3 +/- y)-(SiO2)(x) thin film with x = 0.25 has a suitable cm(-2). dielectric constant of 94.8 and a low leakage current of 1.27 x 10(-8) A The time-dependent dielectric breakdown curve of the 700 degrees C and 800 degrees C annealed SrTiO(3 +/- y)-(SiO2), films with x = 0.25 have an expected lifetime of over 10 years at electric fields higher than 0.6 MV cm(-1).
Electrical and dielectric behavior of fluorite-like Sr0.8Bi2.6Ta2O9 thin films pyrolyzed and thermally annealed at 450 degrees C
(2004-02-15)
Huang, CH
;
Chou, HY
;
Lian, CW
;
Tseng, TY
;
電子工程學系及電子研究所
In this paper, we present the results of the fabrication and characterization of fluorite-like Sr0.8Bi2.6Ta2O9 (SBT) thin films spin-coated on Ir (50 nm)/SiO2 (100 nm)/p-type (100)Si substrates using the metal-organic decomposition (MOD) technique. The SBT films prepared at 450 degreesC under various annealing times were characterized by X-ray diffraction (XRD) as fluorite phase. The polarization versus electric field (P-E) behavior of SBT thin films pyrolyzed and annealed at 450degreesC for 60 min was linear with dielectric constant of 100. The 450 degreesC annealed films have the leakage current density of about 4 x 10(-8) A/cm(2) at 200 kV/cm. The dependence of cumulative failure on dielectric breakdown field and time-dependent dielectric breakdown studies for these paraelectric SBT films indicated that the longer the annealing time, the better the breakdown field, whereas the film with no annealing treatment had a lifetime of over 10 years on operation at the electric field of 0.8 MV/cm. (C) 2003 Elsevier B.V. All rights reserved.
Electrical and dielectric properties of low-temperature crystallized Sr0.8Bi2.6Ta2O9+x thin films on Ir/SiO2/Si substrates
(2003-12-20)
Chou, HY
;
Chen, TM
;
Tseng, TY
;
應用化學系
;
電子工程學系及電子研究所
Ferroelectric thin films of bismuth layer structured compounds, Sr0.8Bi2.6Ta2O9+x (SBT) were deposited onto Ir/SiO2/Si substrates using metal organic decomposition (MOD) method. The crystallization of the SBT thin films annealed at various temperatures was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The polarization (P) versus electric field (E) characteristics exhibited a systematic variation from linear to non-linear polarization (hysteresis) with an increase in the annealing temperature of the SBT films. The leakage current density and dielectric constant of the SBT films were also strongly dependent on the annealing temperature, which in turn determined the grain size, mean surface roughness and inter diffusion through interfacial layers. The lowest leakage current density of 10(-9) A cm(-2) at 100 kV cm(-1) was obtained for SBT thin film annealed at 450 degreesC. The SBT thin films annealed at 650 and 700 degreesC remained fatigue-free up to 10 switching cycles. (C) 2003 Elsevier B.V. All rights reserved.
Variation of electrical properties of Sro(0.8)Bi(2+x)Ta(2)O(9+delta) ferroelectric thin films with bismuth content
(2003)
Chou, HY
;
Tseng, TY
;
Chen, TM
;
應用化學系
;
電子工程學系及電子研究所
In this work, we have investigated the effect of bismuth content on electrical properties of Sr0.8Bi2+xTa2O9+delta (SBT) thin films, obtained by using the metallorganic decomposition technique. The SBT precursor solution was prepared using high purity strontium acetate, bismuth acetate and tantalum ethoxide as the starting materials and acetic acid as the solvent. Thin films were deposited on Ir(50nm)/SiO2(100Mn)/Si substrates by spin coating with precise control of the solution viscosity and spin speed. As-deposited films were dried at 150degreesC for 10 min followed by pyrolysis at 400degreesC for 30 min in static air to remove the solvent and organic impurities. The films were then post-annealed at 650degreesC for 30 min in ambient oxygen atmosphere. The crystallinity of SBT thin films containing various bismuth levels was characterized by X-ray diffraction (XRD). The 30% Bi excess SBT thin films exhibited preferentially (115) oriented phase. The XRD pattern showed all major peaks corresponding to SBT phase. The microstructure, P-E hysteresis loops and leakage current of SBT films were found to be dependent on the bismuth content.