• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.153-156
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• 2004

The $Pb(Zr_{0.4}Ti_{0.6})O_3/Pb(Zr_{0.6}Ti_{0.4})O_3$ [PZT(4060)/(6040)] heterolayered thin films were deposited by RF sputtering method on the $Pt/TiO_2/SiO_2/Si$ substrate. The effects of the structural and dielectric properties of PZT heterolayered thin films were investigated. The MFM(Metal Ferroelectric Metal) type capacitors were made using the PZT(6040)/(4060) heterolayered thin films deposited with optimum deposition condition. An enhanced dielectric property was observed in the PZT(4060)/(6040) thin films. Investigating the dielectric constant and dielectric loss characteristics. the application for the next-generation dielectric thin films and memory devices were studied.

• Journal of Electrical Engineering and Technology
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• v.2 no.3
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• pp.391-395
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• 2007

MgO enhanced $(Ba_{0.6}Sr_{0.4})$ $TiO_3$ thick films have been fabricated by a tape casting and firing method for tunable devices on the microwave frequency band. In order to improve ferroelectric properties, the composite thick films enhanced with MgO on BST have been asymmetrically annealed by a focused halogen beam method. Dielectric constants of composite thick films are changed from 1050 to 1300 at 100 kHz after 60 s and 150 s annealing by the focused halogen beam. Even though no prominent changes were previously observed from the thick films before and after annealing in terms of chemical composition and surface morphology, it is clear that the average particle size of the thick films calculated by Scherrer's formula were increased by annealing. Furthermore, a strong correlation between particle size and dielectric constant of the composite thick films has been observed; dielectric constant increases with increased particle size. This has been attributed to the increased volume of ferroelectric domain due to increased particle sizes. As a result, the tuning range was improved by halogen beam annealing.

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.145-149
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• 2016

$(Bi_{1/2}Na_{1/2})_{0.94}Ba_{0.06}(Ti_{1-x}Nb_x)O_3$ (BNBTxNb) ceramics were investigated in terms of the crystal structure as well as the ferroelectric, dielectric, and piezoelectric properties. While little change was observed in the microstructure except for a slight decrease in the average grain size, a significant change was noticed in the temperature dependence of dielectric and piezoelectric properties. It was shown that the property changes are closely related to the downward shift in the position of the ferroelectric-to-relaxor transition temperature with increasing amount of Nb doping. A special emphasis is put on the fact that Nb doping is so effective at decreasing the ferroelectric-to-relaxor transition temperature that even at no more than 2 at.% Nb addition, the transition temperature was already brought down slightly below room temperature, resulting in the birth of a large strain at 0.46 %, equivalent to $S_{max}/E_{max}=767pm/V$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.11
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• pp.895-899
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• 2011

Multiferroic BFO/PZT(5/95) multilayer films were fabricated by spin-coating method on the Pt/Ti/$SiO_2$/Si substrate alternately using BFO and PZT(9/95) alkoxide solutions. The structural and dielectric properties were investigated with variation of the solvent and the number of coatings. All films showed the typical XRD patterns of the perovskite polycrystalline structure without presence of the second phase such as $Bi_2Fe_4O_3$. BFO/PZT multilayer thin films showed the typical dielectric relaxation properties with increase an applied frequency. The average thickness of 6-coated BFO/PZT multilayer film was about 600 nm. The dielectric properties such as dielectric constant, dielectric loss and remnant polarization were superior to those of single composition BFO film, and those values for BFO/PZT multilayer film were 1199, 0.23% and 12 ${\mu}C/cm^2$.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.30.1-30.1
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• 2011

Multiferroic thin films with composition $0.9BiFeO_3-0.1Ba(Cu_{1/3}Nb_{2/3})O_3$ were epitaxially grown by pulsed laser deposition on $SrRuO_3(001)/SrTiO_3$ (000) substrate $0.9BiFeO_3-0.1Ba(Cu_{1/3}Nb_{2/3})O_3$, which is assumed to be morphotropic phase boundary (MPB), that showed superior dielectric, ferroelectric and magnetic properties in our study on polycrystalline films. The structures of epitaxially grown films were characterized by means of XRD. From P-E measurements, samples exhibited typical ferroelectric hysteresis loops and large remnant polarization, whose value is much larger than those of pure BFO film. The enhancement of dielectric, ferroelectric, magnetic properties was attributed to the structural distortion induced by the BCN addition and the high physical stress effect.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.455-458
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• 2001

The thin films of high pemitivity in ferroelectric materials using a capacitor are applied to DRAMs and FRAMs. (Ba, Sr)$TiO_3$ thin films as ferroelectric materials were prepared by the sol-gel method and made by spin-coating on the Pt/Ti/$SiO_2/Si$ substrate at 4,000 [rpm] for 10 seconds. The devices of BST thin films to composite $(Ba_{0.7},Sr_{0.3})TiO_3$ were fabricated by changing of the depositing layer number on $Pt/Ti/SiO_2/Si$ substrate. The thin film capacitor to be ferroelectric devices was investigated by structural and electrical properties. The thickness of BST thin films at each coating numbers 3, 4 and 5 times was $2500[\AA]$, $3500[\AA]$, $3800[\AA]$. The dielectric factor of thin film when the coating numbers were 3, 4 and 5 times was 190, 400 and 460 on frequency l[MHz]. The dielectric loss of BST thin film was linearly increased by increasing of the specimen area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.455-458
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• 2001

The thin films of high permitivity in ferroelectric materials using a capacitor are applied to DRAMs and FRAMs. (Ba, Sr)TiO$_3$ thin films as ferroelectric materials were prepared by the sol-gel method and made by spin-coating on the Pt/Ti/SiO$_2$/Si substrate at 4,700 [rpm] for 10 seconds. The devices of BST thin films to composite (Ba$\_$0.7/Sr$\_$0.3/)TiO$_3$ were fabricated by changing of the depositing layer number on Pt/Ti/SiO$_2$/Si substrate. The thin film capacitor to be ferroelectric devices was investigated by structural and electrical properties. The thickness of BST thin films at each coating numbers 3, 4 and 5 times was 2500[${\AA}$], 3500[${\AA}$], 3800[${\AA}$]. The dielectric factor of thin film when the coating numbers were 3, 4 and 5 times was 190, 400 and 460 on frequency 1[MHz]. The dielectric loss of BST thin film was linearly increased by increasing of the specimen area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.660-663
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• 2001

The devices of BST thin films to composite (Ba$\_$0.7/ Sr$\_$0.3/)TiO$_3$using sol-gel method were fabricated by changing of the depositing layer number on Pt/Ti/SiO$_2$/Si substrate. The thin film capacitor to be ferroelectric devices was investigated by structural and electrical properties. The thickness of BST thin films at each coating numbers 3, 4 and 5 times was 2500[${\AA}$], 3500[${\AA}$], 3800[${\AA}$]. The dielectric factor of thin film when the coating numbers were 3, 4 and 5 times was 190, 400 and 460 on frequency 1[MHz]. The dielectric loss of BST thin film was linearly increased by increasing of the specimen area.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.190-194
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• 2003

Dielectric thin films of (P $b_{0.72}$,L $a_{0.28}$) $Ti_{0.93}$ $O_3$ (PLT(28)) have been deposited on Pt(111)/Ti/ $SiO_2$/Si(100) substrates in-situ by pulsed laser deposition using different annealing and deposition Processes. We have investigated the effect of hydrogen annealing on the ferroelectric properties of PLT thin films and found that the annealing process causes the diffusion of hydrogen into the ferroelectric film resulting in the destruction of polarization. We have tried to form the film by a two-step deposition process In order to improve electrical property. Two-step process to grow PLT films was adopted and verified to be useful to enlarge the grain size of the film and to reduce the leakage current characteristics. Structural properties and electrical properties including dielectric constant, ferroelectric characteristics, and leakage current of PLT thin films were shown to be strongly influenced by grain size. The film deposited by using two-step Process including pre-annealing treatment has a strongly(111) orientation. However, the films deposited by using single -step process with hydrogen annealing process show the smallest grain size. The film deposited by using two-step process including pre-annealing treatment shows the leakage current density of below 10$^{-7}$ A/c $m^2$ for the field of smaller than 100 kV/cm. However, the films deposited by using single-step process with hydrogen annealing process and pre-annealing process show worse leakage current density than the film deposited by using two-step process including pre-annealing treatment.tment.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1618-1620
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• 2004

The $Pb(Zr_{0.4}Ti_{0.6})O_3/Pb(Zr_{0.6}Ti_{0.4})O_3$ [PZT(4060)/(6040)] multilayered thin films were deposited by RF Sputtering method on the Pt/Ti/$SiO_2$/Si substrate. This procedure was repeated several times to form PZT(4060)/(6040) heterolayerd thin films. The effects on the structural and dielectric properties of PZT multilayered thin films were investigated. The MFM(Metal Ferroelectric Metal) type capacitors were made using the PZT(4060)/(6040) multilayered thin films deposited with optimum deposition condition. An enhanced dielectric property was observed in the PZT(4060)/(6040) multilayered thin films. The relative dielectric constant and dielectric loss at 100Hz of the PZT(4060)/(6040)-5 multilayered thin films were about 1106 and 0.016, respectively.