Browsing by Author "Sun, CL"

Now showing 1 - 13 of 13

Bi3.25La0.75Ti3O12 thin films on ultrathin Al2O3 buffered Si for ferroelectric memory application
(2002-04-29)
Chen, SY
;
Sun, CL
;
Chen, SB
;
Chin, A
;
材料科學與工程學系
We have investigated the physical and electrical properties of Bi3.25La0.75Ti3O12 (BLT) thin films on Pt/Ti/SiO2/Si and on Al2O3(6 nm)/Si, which are used for one-transistor-one-capacitor and one-transistor ferroelectric memory, respectively. The BLT thin films on both substrates show good capacitance-voltage characteristics and the same threshold voltage shift of 1.6 V at applied +/-10 V bias. However, the leakage current of BLT on Al2O3/Si at -100 kV/cm is two orders of magnitude lower than that on Pt. The comparable memory characteristics and much reduced leakage current of BLT on Al2O3/Si are the strong advantages as compared with BLT on Pt because it is directly related to switching energy and device scaling down. (C) 2002 American Institute of Physics.
Characteristics of Pb(Zr0.53Ti0.47)O-3 on metal and Al2O3/Si substrates
(2001-11-01)
Sun, CL
;
Chen, SY
;
Yang, MY
;
Chin, A
;
材料科學與工程學系
We have fabricated Pb(Zr0.53Ti0.47)O-3 on Pt and Pb(Zr0.53Ti0.47)O-3 on 4 nm Al2O3/Si substrates. Although Pb(Zr0.53Ti0.47)O-3 on Pt has a larger dielectric constant and grain size than those on Al2O3/Si, the Pb(Zr0.53Ti0.47)O-3 thin films on both substrates show good capacitance-voltage characteristics and the same threshold voltage shift of similar to3.6 V. Moreover, the leakage current density of Pb(Zr0.53Ti0.47)O-3 on Al2O3/Si at -10 V is nearly three orders of magnitude lower than that of Pb(Zr0.53Ti0.47)O-3 on Pt. The comparable memory characteristics and the lower leakage current of Pb(Zr0.53Ti0.47)O-3 on Al2O3/Si are important for continuous scaling down the ferroelectric memory. (C) 2001 The Electrochemical Society.
Characterization of BaPbO3 and Ba(Pb1-xBix)O-3 thin films
(2002-02-17)
Sun, CL
;
Wang, HW
;
Chang, MC
;
Lin, MS
;
Chen, SY
BaPbO3 and Ba(Pb1-xBix)O-3 films made from barium 2-ethylhexanoate, lead 2-ethylhexanoate and bismuth acetate were prepared by metal-organic deposition (MOD) method on Pt/Ti/SiO2/Si substrate. The phase transition and the physical properties of these films were studied. The polycrystalline BaPbO3 phase starts to form above 600 degreesC and the Pb-excess addition would enhance the formation of single perovskite BaPbO3 phase. With increasing annealing temperature, the optimum sheet resistance 1.6 Omega sq(-1) (resistivity approximate to 1.07 x 10(-4) Omega cm) could be obtained at 750 degreesC. However, an annealing temperature over 800 degreesC causes reactions between substrate and BaPbO3 phase and results in sharp increase of resistance. On the other hand, the substitution of Pb by Bi in the Ba(Pb1-xBix)O-3 films could stabilize the perovskite phase, though the sheet resistance is raised over 10 Omega sq(-1) at x = 0.3. (C) 2002 Elsevier Science B.V. All rights reserved.
Characterization of BaPbO3 and Ba(Pb1-xBix)O-3 thin films
(2003-02-17)
Sun, CL
;
Wang, HW
;
Chang, MC
;
Lin, MS
;
Chen, SY
BaPbO3 and Ba(Pb1-xBix)O-3 films made from barium 2-ethylhexanoate, lead 2-ethylhexanoate and bismuth acetate were prepared by metal-organic deposition (MOD) method on Pt/Ti/SiO2/Si substrate. The phase transition and the physical properties of these films were studied. The polycrystalline BaPbO3 phase starts to form above 600 degreesC and the Pb-excess addition would enhance the formation of single perovskite BaPbO3 phase. With increasing annealing temperature, the optimum sheet resistance 1.6 Omega sq(-1) (resistivity approximate to 1.07 x 10(-4) Omega cm) could be obtained at 750 degreesC. However, an annealing temperature over 800 degreesC causes reactions between substrate and BaPbO3 phase and results in sharp increase of resistance. On the other hand, the substitution of Pb by Bi in the Ba(Pb1-xBix)O-3 films could stabilize the perovskite phase, though the sheet resistance is raised over 10 Omega sq(-1) at x = 0.3. (C) 2002 Elsevier Science B.V. All rights reserved.
Effect of annealing temperature on physical and electrical properties of Bi3.25La0.75Ti3O12 thin films on Al2O3-buffered Si
(2002-03-18)
Sun, CL
;
Chen, SY
;
Chen, SB
;
Chin, A
;
材料科學與工程學系
The effect of annealing temperature, especially at high temperatures, on the physical and electrical properties of Bi3.25La0.75Ti3O12 (BLT) thin films on Al2O3 (10 nm)/Si has been investigated. The width of memory window in capacitance-voltage curves for BLT/Al2O3/Si capacitors annealed at temperature range of 700 degreesC-950 degreesC increases with increasing annealing temperature. At the highest annealing temperature of 950 degreesC, a large ferroelectric memory window of 13 V is obtained under +/-15 V sweep voltage, and this large ferroelectric memory window should be related to the reduced leakage current. Owing to the excellent electrical properties, the high-temperature stable BLT/Al2O3/Si capacitor is compatible with current very large scale integrated technology process. (C) 2002 American Institute of Physics.
Effect of Zr/Ti ratios on characterization of Pb(ZrxTi1-x)O-3 thin films on Al2O3 buffered Si for one-transistor memory applications
(2003-03-01)
Sun, CL
;
Hsu, JJ
;
Chen, SY
;
Chin, A
;
材料科學與工程學系
Pb(ZrxTi1-)O-3 (PZT) thin films have been prepared on Al2O3/Si and PbTiO3/Al2O3/Si substrates, respectively. On Al2O3/Si substrates, Ti-rich PZT thin films had lower perovskite transformation temperatures than those of Zr-rich PZT films. Therefore, PbTiO3 was used as the seeding layer on Al2O3/Si to form a PbTiO3/Al2O3/Si substrate. The threshold voltage shift of a PZT(53/ 47)/PbTiO3/Al2O3/Si capacitor reaches 9 V with +/-10 V writing voltages, which is much larger than the 2 V of the PZT(0/100)/PbTiO3/Al2O3/Si capacitor. Different memory mechanisms in the capacitance-voltage characteristics of capacitors were further examined and discussed in this paper. (C) 2003 The Electrochemical Society.
Electrical and structural characteristics of PbTiO3 thin films with ultra-thin Al2O3 buffer layers
(2003-02-17)
Sun, CL
;
Chen, SY
;
Yang, MY
;
Chin, A
;
材料科學與工程學系
Polycrystalline PbTiO3 thin films have been prepared on Si substrates with ultra-thin SiO2 and Al2O3 buffer layers by chemical solution deposition, respectively. Although capacitance-voltage characteristics show hysteresis loops in both cases, the memory window of PbTiO3/Al2O3 stacked dielectric is 3.3V larger than that on SiO2. In addition, well-behaved capacitance-voltage characteristics are only obtained in PbTiO3/Al(2)o(3) and the PbTiO3 films on Al2O3 have the dielectric constant of 116 larger than 42 of PbTiO3 films on SiO2. The leakage current density of PbTiO3/Al2O3 dielectric is 1.3 x 10(-7) A cm(-2) at -2.5 V, which is low enough for deep sub-mum application. (C) 2002 Elsevier Science B.V. All rights reserved.
Electrical and structural characteristics of PbTiO3 thin films with ultra-thin Al2O3 buffer layers
(2002-02-17)
Sun, CL
;
Chen, SY
;
Yang, MY
;
Chin, A
;
材料科學與工程學系
Polycrystalline PbTiO3 thin films have been prepared on Si substrates with ultra-thin SiO2 and Al2O3 buffer layers by chemical solution deposition, respectively. Although capacitance-voltage characteristics show hysteresis loops in both cases, the memory window of PbTiO3/Al2O3 stacked dielectric is 3.3V larger than that on SiO2. In addition, well-behaved capacitance-voltage characteristics are only obtained in PbTiO3/Al(2)o(3) and the PbTiO3 films on Al2O3 have the dielectric constant of 116 larger than 42 of PbTiO3 films on SiO2. The leakage current density of PbTiO3/Al2O3 dielectric is 1.3 x 10(-7) A cm(-2) at -2.5 V, which is low enough for deep sub-mum application. (C) 2002 Elsevier Science B.V. All rights reserved.
Ferroelectric characteristics of oriented Pb(Zr1-xTix)O-3 films
(2001-09-15)
Chen, SY
;
Sun, CL
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Pb1.2Zr1-xTix)O-3 (PZT) films with a variety of compositions were prepared by spin coating on Pt/Ti/SiO2/Si substrate with sol-gel processing. The roles of composition (phase) and orientation in ferroelectric properties of PZT films have been determined. The Zr-rich PZT films with (111)-oriented PZT films have a higher remanent polarization but also show a higher fatigue rate as compared to (100)-oriented films in both Zr-rich(65/35) and Ti-rich(35/65) PZT compositions. The lower fatigue rate of (100)-oriented film can be attributed to its easier reversible domain-wall motions compared to (111)-oriented PZT films due to the absence of internal field stress and less dependence on electrical field. A mode based on domain-wall contribution instead of film-electrode interface is favored to elucidate the role of orientation in fatigue characteristics of PZT films. (C) 2001 American Institute of Physics.
Low voltage lead titanate/Si one-transistor ferroelectric memory with good device characteristics
(2004-11-15)
Sun, CL
;
Chen, SY
;
Liao, CC
;
Chin, A
;
材料科學與工程學系
We have developed one-transistor ferroelectric memory using lead titanate (PTO) as a gate dielectric directly formed on Si without any buffer layer. The PTO/Si metal-oxide-semiconductor field-effect transistor memory has shown a large threshold voltage shift of 1.6 V at only +/-4 V program/erase voltages. The corresponding good interface was achieved by lowering the anneal temperature to 450 degreesC. Besides the sharp capacitance change of 0.17 muF/V cm(2), it was also evidenced by the high mobility of 169 cm(2)/V s close to high-kappa HfO2. In addition, long retention >1000 s and endurance >10(11) stress cycles in the device suggested good memory characteristics. (C) 2004 American Institute of Physics.
Role of interface reaction at high temperature in electrical characteristics of Bi3.25La0.75Ti3O12/Al2O3/Si capacitors
(2003-09-01)
Sun, CL
;
Chen, SY
;
材料科學與工程學系
;
Department of Materials Science and Engineering
A novel face-to-face annealing process was used to investigate the enhanced electrical characteristics in Bi3.25La0.75Ti3O12 (BLT)/Al2O3/Si capacitors annealed at high temperatures. The low leakage current of BLT/Al2O3/Si capacitors can be obtained after high temperature annealing and the mechanism has been clarified and attributed to the formation of Si-rich aluminum oxide. The surface composition of aluminum oxide after annealing was further analyzed by X-ray photoelectron spectrometer (XPS) and XPS spectra revealed that the aluminum oxide would react with both Si substrate and BLT thin films to form Si-rich aluminum oxide. Because the aluminum oxide has weaker bonding than that of silicon oxide, Si composition can quench the electrical defects in aluminum oxide so as to reduce the leakage current of BLT/Al2O3/Si capacitors. (C) 2003 The Electrochemical Society.
Stack gate PZT/Al2O3 one transistor ferroelectric memory
(2001-07-01)
Chin, A
;
Yang, MY
;
Sun, CL
;
Chen, SY
;
材料科學與工程學系
We have developed single transistor ferroelectric memory using stack gate PZT/Al2O3 structure. For the same similar to 40 Angstrom dielectric thickness, the PZT/Al2O3/Si gate dielectric has much better C-V characteristics and larger threshold voltage shift than those of PZT/SiO2/Si. Besides, the ferroelectric MOSFET also shows a large output current difference between programmed on state and erased off state, The <100 ns erase time is much faster than that of Flash memory where the switching time is limited by erase time.
Ultrafine platinum nanoparticles uniformly dispersed on arrayed CNx nanotubes with high electrochemical activity
(2005-07-12)
Sun, CL
;
Chen, LC
;
Su, MC
;
Hong, LS
;
Chyan, O
The structure and electrochemical properties of arrayed nitrogen-containing carbon nanotube (CN, NT)-platinum nanoparticle (Pt NP) composites directly grown on Si substrates have been investigated. The CN., nanotube arrays were grown by microwave-plasma-enhanced chemical vapor deposition first and then acted as the template and support for Pt dispersion in the following sputtering process. Under the same sputtering conditions, it was found that well-separated Pt NPs would form with an average diameter of 2 nm on the arrayed NTs while a continuous Pt thin film was observed on the bare Si substrate. X-ray photoelectron spectroscopy (XPS), X-ray diffraction, and electron microscopy were employed to study bonding and structure changes with increasing deposition time. Implications of the C1s and N1s bonding changes in XPS and their possible relation to the NT-Pt composite structures with self-limited size distribution are discussed. Cyclic voltammograms show well-behaved curves in methanol oxidation, suggesting an efficient electronic conduction mechanism from the substrate via CN, NTs to reach individual Pt NPs is in operation. Such an integrated nanocomposite approach possesses a high potential for micro direct methanol fuel cell applications.