• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.155-158
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• 2002

Eu-doped lead zirconium titanate $Pb_{1.1}(Zr_{0.3}Ti_{0.7})O_{3}$ thin films on the Pt/Ti/$SiO_2$/Si substrates prepared by a metalorganic decomposition (MOD) method. The effect on the structural and electrical properties of the films measured according to Eu content. Eu-doping altered significantly the dielectric and ferroelectric properties. The remanent polarization and coercive field decreased with increasing the concentration of Eu content. The dielectric constant and dielectric loss of the film decreased with increasing Eu contents. The 3 mol% of Eu-doped PZT thin film showed large remanent polarization and the fatigue characteristic of the film did not change up to $10^9$ switching cycles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.309-312
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• 2002

Ferroelectric $Sr_{0.3}Ba_{0.7}Nb_{2}O_{6}$ (SBN30) thin films were deposited on Pt/Ti/$SiO_{2}$/Si(100) substrates by ion beam sputtering. During annealing treatment at $750^{\circ}C$, poling was attempted by applying dc voltage bias across polished surfaces. Phase relation, microstructure and crystallization behavior were examined using XRD and FE-SEM. Ferroelectric hysteresis characteristics were also determined where both remanent polarization and coercive values decreased with the increase of bias voltage. The measured remanent polarization and coercive field values at 5 V and 10 V bias were $36{\mu}C/cm^2$, $10{\mu}C/cm^2$ and 100kV /cm, 80kV /cm, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.113-117
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• 1999

SrBi$_2$Ta$_2$$O_{9}$ (SBT) thin films were fabricatcd with different Sr/Bi ratios by MOD. SBT thin films of thickness 2500$\AA$ deposited on Pt/Ti/SiO$_2$/Si were crystallized at $700^{\circ}C$ ~85$0^{\circ}C$ using RTA method. As the Sr/Bi ratio was decreased, dielectric constant and remanent polarization were increased. SrBi$_2$Ta$_2$$O_{9}$ showed a maximum dielectric constant value of $\varepsilon$$_{r}$= 268, and maximum remanent polarization (2Pr) of ~9.86 $\mu$C/$\textrm{cm}^2$ when annealed at 8$0^{\circ}C$ for 8 min.min.n.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.474-475
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• 2007

The $Sr_{0.8}Bi_{2.2}Ta_2O_9$(SBT) thin films are deposited on Pt-coated electrode(Pt/$TiO_2/SiO_2$/Si) using RF magnetron sputtering method. The aging properties of SBT capacitor with top electrodes represents a favorable properties in Pt electrode. The dielectric constant and leakage current density with Pt electrode is 340 and $6.81{\times}10^{-10}\;A/cm^2$ respectively. The maximum remanent polarization and the coercive electric field with Pt electrode are $12.40{\mu}C/cm^2$ and 30kV/cm respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.67-69
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• 2004

The $Pb(Zr,Ti)O_3$ thin films were fabricated with $Pb(La,Ti)O_3$ buffers in-situ onto $Pt/Ti/SiO_2/Si$ substrates by pulsed laser deposition technique using a Nd:YAG laser with energy density of $2.5J/cm^2$, and deposited for 10 minutes at $550^{\circ}C$ of substrate temperature. And then, the films have been annealed at $550^{\circ}C$ in oxygen ambient pressure. The remanent polarization value is increased by using buffer layers but coercive field of films is slightly increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.09a
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• pp.9-12
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• 2001

The $Sr_{0.8}Bi_{2.4}Ta_2O_9(SBT)$ thin films are deposited on Pt-coated electrode($Pt/TiO_2/SiO_2/Si$) using RF magnetron sputtering method. With increasing post-annealing temperature from $600[^{\circ}C]$ to $850[^{\circ}C]$, Bi-layered perovskite phase was crystallized above $650[^{\circ}C]$. The maximum remanent polarization and the coercive electric field is 11.60[${\mu}C/cm^{2}$] 48[kV/cm] respectively. The leakage current density of SBT capacitor at post-annealing temperature of $750[^{\circ}C]$ is $1.01{\times}10^{-8}A/cm^2$ at 100[kV/cm]

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.5
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• pp.370-375
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• 2001

PZT thin films (3500${\AA}$) ahve been prepared onto Pt/Ti/corning glass (1737) substrates with a RF magnetron sputtering system using Pb$\sub$1.50/(Zr$\sub$0.52/,Ti$\sub$0.48)O$_3$ ceramic target. We used two-step annealing techniques, PZT thin films were grown at a 300$^{\circ}C$ substrate temperature and then subjected to an RTA treatment. In case of 500$^{\circ}C$ RTA temperature show pyrochlore phase. The formation of Perovskite phase started above 600$^{\circ}C$ and PZT thin films generated (101) preferred orientation. As the RTA time and temperature increased, crystallization of PZT films were enhanced. The PZT capacitors fabricated at 650$^{\circ}C$ for 10 minutes RTA treatment showed remanent polarization 30 ${\mu}$C/$\textrm{cm}^2$, saturation polarization 42${\mu}$C/$\textrm{cm}^2$, coercive field 110kV/cm, leakage current density 2.83x10$\^$-7/A/$\textrm{cm}^2$, remanent polarization were decreased by 30% after 10$\^$9/ cycles.

• Journal of Electrical Engineering and Technology
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• v.2 no.1
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• pp.98-101
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• 2007

Yttrium(Y)-substituted bismuth titanate $(Bi_{4-x},Y_x)Ti_3O_{12}$ [x=0, 0.25, 0.5, 0.75, 1](BYT) thin films were deposited using an RF sputtering method on the $Pt/TiO_2/SiO_2/Si$ substrates. The structural properties and electrical properties of yttrium-substituted $(Bi_4-xYx)Ti_3O_{12}$ thin films were analyzed. The remanent polarization of $(Bi_4-xYx)Ti_3O_{12}$ films increased with increasing Y-content. The $(Bi_{3.25}Y_{0.75})Ti_3O_{12}$ films fabricated using a top Au electrode showed saturated polarization-electric field(P-E) switching curves with a remanent polarization(Pr) of $8{\mu}C/cm^2$ and coercive field (Ec) of 53 kV/cm at an applied voltage of 7 V. The $(Bi_{3.25}Y_{0.75})Ti_3O_{12}$ films exhibited fatigue-free behavior up to $4.5{\times}10^{11}$ read/write switching cycles at a frequency of 1MHz.

• The Korean Journal of Ceramics
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• v.6 no.2
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• pp.138-142
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• 2000

Thin film $LiNbO_3$MFS (metal-ferroelectric-semiconductor) capacitor showed improved characteristics such as low interface trap density, low interaction with Si substrate, and large remanent polarization. This paper reports ferroelectric $LiNbO_3$thin films grown directly on p-type Si (100) substrates by 13.56 MHz RF magnetron sputtering system for FRAM (ferroelectric random access memory) applications. RTA (rapid thermal anneal) treatment was performed for as-deposited films in an oxygen atmosphere at $600^{\circ}C$ for 60sec. We learned from X-ray diffraction that the RTA treated films were changed from amorphous to poly-crystalline $LiNbO_3$which exhibited (012), (015), (022), and (023) plane. Low temperature film growth and post RTA treatments improved the leakage current of $LiNbO_3$films while keeping other properties almost as same as high substrate temperature grown samples. The leakage current density of $LiNbO_3$films decreased from $10^{-5}$ to $10^{-7}$A/$\textrm{cm}^2$ after RTA treatment. Breakdown electric field of the films exhibited higher than 500 kV/cm. C-V curves showed the clockwise hysteresis which represents ferroelectric switching characteristics. Calculated dielectric constant of thin film $LiNbO_3$illustrated as high as 27.9. From ferroelectric measurement, the remanent polarization and coercive field were achieved as 1.37 $\muC/\textrm{cm}^2$ and 170 kV/cm, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.48-55
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• 2024

The changes in threshold voltage and DIBL were investigated for changes in remanent polarization P_r and coercive field E_c, which determine the characteristics of the P-E hysteresis curve of ferroelectric in NCFET (negative capacitance FET). The threshold voltage and DIBL (drain-induced barrier lowering) were observed for a junctionless double gate MOSFET using a gate oxide structure of MFMIS (metal-ferroelectric-metal-insulator-semiconductor). To obtain the threshold voltage, series-type potential distribution and second derivative method were used. As a result, it can be seen that the threshold voltage increases when P_r decreases and E_c increases, and the threshold voltage is also maintained constant when the P_r/E_c is constant. However, as the drain voltage increases, the threshold voltage changes significantly according to P_r/E_c, so the DIBL greatly changes for P_r/E_c. In other words, when P_r/E_c=15 pF/cm, DIBL showed a negative value regardless of the channel length under the conditions of ferroelectric thickness of 10 nm and SiO₂ thickness of 1 nm. The DIBL value was in the negative or positive range for the channel length when the P_r/E_c is 25 pF/cm or more under the same conditions, so the condition of DIBL=0 could be obtained. As such, the optimal condition to reduce short channel effects can be obtained since the threshold voltage and DIBL can be adjusted according to the device dimension of NCFET and the P_r and E_c of ferroelectric.