• 한국전기전자재료학회논문지
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• 제27권5호
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• pp.297-302
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• 2014

$La_{0.5}Sr_{0.5}CoO_3$ (LSCO) electrode thin films with a resistivity of ~ 1,600 ${\mu}{\Omega}cm$ were grown on c-$Al_2O_3$ (0001) substrate. $ZnSnO_3$ (ZTO) thin films with different thicknesses were directly grown on LSCO/c-$Al_2O_3$ (0001) substrates at a substrate temperature that ranged from 550 to $750^{\circ}C$ using Pulsed Laser Deposition (PLD). The secondary phase $Zn_2SnO_4$ occurred during the growth of ZTO films and it became more significant with further increasing substrate temperature. Polarization-electric-field (P-E) hysteresis characteristics, with a remnant polarization and coercive field of 0.05 ${\mu}C/cm^2$ and 48 kV/cm, respectively, were obtained in the ZTO film grown at $700^{\circ}C$ in 200 mTorr.

• Transactions on Electrical and Electronic Materials
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• 제14권3호
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• pp.130-132
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• 2013

$Bi_{3.25}La_{0.75}Ti_3O_{12}$(BLT) thin films were prepared on the Pt(150 nm)/Ti(50 nm)/$SiO_2$/Si substrate using the rf magnetron sputtering method. The BLT thin films were annealed at temperatures ranging from $600^{\circ}C$ to $750^{\circ}C$ using the rapid thermal annealing. The structure and surface morphology of the thin films were characterized by x-ray diffraction and field emission scanning electron microscopy. The hysteresis loop of the BLT thin films showed that the remanent polarization (2Pr) of the film annealed at $700^{\circ}C$ was 10.92 ${\mu}C/cm^2$. The fatigue characteristic of the BLT thin film annealed at $700^{\circ}C$ was shown change polarization up to $1.2{\times}10^9$ switching cycles. We confirmed the excellent remnant polarization (Pr) and fatigue properties compared with other fabrication methods and suggested a good method for BLT thin films fabrications.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.73-74
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• 2006

Ferroelectric thin films have been widely investigated for future nonvolatile memory application. We fabricated the BLT ($(Bi,La)_4Ti_3O_{12}$) films on Si using a STA ($SrTa_2O_6$) buffer layer BLT and STA film were prepared by sol-gel method. Measurement data by XRD and AFM, showed that BLT film and STA films were well crystallized and a good surface morphology. From C-V measurement reward that the Au/BLT/STA/Si structure showed a clockwise hysteresis loop with a memory window of 1.5 V for the bias voltage sweep of ${\pm}5$ V. From results, the Au/BLT/STA/Si structure is useful for FeFETs.

• 한국전기전자재료학회논문지
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• 제14권7호
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• pp.551-556
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• 2001

In this work, the recovery of etching damage in the etched PZT thin film with $O_2$ annealing has been studied. The PZT thin films were etched as a function of Cl$_2$/Ar and additive CF$_4$ into Cl$_2$(80%) /Ar(20%). the etch rates of PZT thin films were 1600$\AA$/min at Cl$_2$(80%)/Ar(20%) and 1970 $\AA$/min at 30% additive Cf$_4$ into Cl$_2$(80%)/Ar(20%). In order to recover the characteristics of etched PZT thin films, the etched PZT thin films were annealed in $O_2$ atmosphere at various temperatures. From the hysteresis curves, ferroelectrical properties are improved by $O_2$ annealing process. The improvement of ferroelectric behavior is consistent with the increase of the (100) and (200) PZT phase revealed by x-ray diffraction (XRD). From x-ray photoelectron spectroscopy (XPS) analysis, intensities of Pb-O, Zr-O and Ti-O peak increase and the chemical residue peak is reduced by $O_2$ annealing. From the atomic force microscopy (AFM) images. it shows that the surface morphology of re-annealed PZT thin films after etching is improved.

• Transactions on Electrical and Electronic Materials
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• 제1권1호
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• pp.22-25
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• 2000

Polycrystalline SBTN layered ferroelectric thin film with various Nb mole ratios were prepared by sol-gel method Pt/ $SiO_2$/Si (100) substrates. The films were annealed at different temperature and characterized in terms of phase and microstructure. The films were crystallized with a high (105) diffraction intensity and had rodike structure, SBTN films fired at 800$^{circ}C$ revealed standard hysteresis loops with no fatigue for up to 10$^{10}$ cycles. At an applied voltage of 5V the dielectric constant($varepsilon$) , dissipation factor (tan $delta$), remanent polarization(ZPr) and coercive field(Ec) of typical S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$) $O_{9+}$$alpha$/ thin film(x=0.1) prepared on Pt/ $SiO_2$/Si (100) were about 277.7, 0.042, 3.74$mu$C/$textrm{cm}^2$, and 24.8kv/cm respectively.ly.y. respectively.ly.y.y..

• Journal of Advanced Marine Engineering and Technology
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• 제30권8호
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• pp.894-900
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• 2006

The electrical characteristics associated with crystal structure changes as a function of La content for $(Pb_{1-x}La_x)(Zr_{0.5}Ti_{0.5})O_3$ thin films were investigated for applications in memory capacitors. Tetragonality of PLZT films decreased with increasing La content. Thin films with La $\geq$ 20 mol% were found to be cubic. Films with La $\geq$ 12 mol% exhibited broader dielectric peaks compared to those of bulk ceramics and behaved as relaxer ferroelectrics. Tetragonal PLZT film with 12 mol% La had a dielectric constant maximum of 1330 at room temperature and a charge storage density of ${\sim}18{\mu}C/cm^2$ at 5 V. Decrease in coercive field and remnant polarization with increase in La content were resulting from less dipolar response caused by the decreased crystal anisotropy. The leakage current densities $<10^{-8}A/cm^2$ up to 5 V bias voltage were observed for the films with La $\geq$ 14 mol%.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.323-323
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• 2012

We present ferroelectricity of Bi-doped ZnO film probed by piezoresponse force microscopy (PFM), which is one of the Scanning Probe Microscopy techniques. Perovskite ferroelectrics are limited to integration of devices into semiconductor microcircuitry due to hard adjusting their lattice structure to the semiconductor materials. Transition metal doped ZnO film is one of the candidate materials for replacing the perovskite ferroelectrics. In this study, ferroelectric characteristics of the Bi-doped ZnO grown by pulsed laser deposition were probed by PFM. The polarization switching and patterning of the ZnO films were performed by applying DC bias voltage between the AFM tips and the films with varying voltages and polarity. The PFM contrast before and after patterning showed clearly polarization switching for a specific concentration of Bi atoms. In addition, the patterned regions with nanoscale show clearly the local piezoresponse hysteresis loop. The spontaneous polarization of the ZnO film is estimated from the local piezoresponse based on the comparison with LiNbO3 single crystals.

• 한국전기전자재료학회논문지
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• 제13권8호
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• pp.694-699
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• 2000

S $r_{0.9}$/B $i_{2.1}$/T $a_{2}$/ $O_{9}$ solutions was synthesized by MOD (metalorganic decomposition) method. SBT thin films with 2000$\AA$ thickness were prepared on Ir $O_2$/ $SiO_2$/Si and Pt/Ti/ $SiO_2$/Si substrates using the spin coating process and then investigated the dielectric and electrical properties of them. In the case of using Ir $O_2$bottom electrode the hysteresis loop was saturated at lower temperature than Pt/Ti electrode but the breakdown phenomenon was occurred at low voltage because of the rough surface morphology and porous microstructure of SBT thin films. As the results of the fatigue and imprint characteristics related to the lifetime and reliability of devices after 10$^{10}$ cycles the fatigue rates were about 10% at the Ir $O_2$and Pt/Ti bottom electrodes. Both SBT thin films with Ir $O_2$ and with Pt/Ti bottom electrodes show a slight tendency to imprint after 10$^{9}$ cycles but do not lead to a failure.e.e.

• Journal of Magnetics
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• 제14권3호
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• pp.117-119
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• 2009

Polycrystalline samples of LaFe$O_3$-BaTi$O_3$ were synthesized to examine the structural and magnetic behavior. X-ray diffraction confirmed that the ceramics had tetragonal symmetry with less tetragonal strain (c/a) than BaTi$O_3$. The magnetic hysteresis measured at room temperature suggested that the magnetic nature deviates from that of the parent LaFe$O_3$, which has antiferromagentic with a G-type spin structure. Improved magnetic behavior of the solid solution compound might be due to the increase in the canting angle of the spin. The presence of oxygen vacancies and fluctuating Fe valence, arising from the substitution of $Ba^{2+}$ and $Ti^{4+}$ at the A- and B-sites of the lattice, might contribute to bulk magnetization. The temperature dependent magnetization indicated that magnetization was higher at low temperatures and showed a decreasing trend with increasing temperature to room temperature. The magnetic transition temperature of these samples was 665 K and 743 K for the mixed system and LaFe$O_3$, respectively.

• 대한전자공학회논문지SD
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• 제37권4호
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• pp.7-14
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• 2000

Bi/sub 4/Ti/sub 3/O/sub 12/ (BIT) 박막을 acetate 계 precursor 를 이용한 sol-gel 법으로 제작한 후, 구조적 및 전기적 특성을 조사하여 NVFRAM (Won-Volatile Ferroelectric RAM)으로의 응용가능성을 조사하였다. DT-TG (Differential Thermal-Thermal Gravimetric) 분석으로 drying 온도와 annealing 온도가 각각 400℃ 와 650℃ 인 BIT 박막의 열처리조건을 확립하였다. Pt/Ta/Sio/sub 2//Si 기판 위에 제작된 BIT 박막은 완전한 orthorhombic perovskite상을 가지며, 입자크기가 약 100nm 이고 표면 거칠기는 약 70.2Å 으로 비교적 치밀한 형상을 나타내었다. 10㎑ 의 주파수에서 비유전률과 유전손실은 각각 176 과 0.038 이었으며, 100 ㎸/cm 의 전기장에서 누설전류밀도는 4.71㎂/㎠ 이었다. ±250㎸/㎝ 에서 이력곡선을 측정한 결과, 잔류분극 (Pr)과 항전계 (Ec)는 각각 5.92μC/㎠ 과 86.3㎸/㎝ 이었다. BIT 박막에 ±5V 의 사각펄스를 인가하여 피로특성을 측정한 결과, 잔류분극은 초기값 5.92μC/㎠ 에서 10/sup 9/회에서는 3.95μC/㎠ 로 약 33% 감소하였다.