• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.94-98
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• 2000

Polycrystalline SBTN ferroelectric thin films were prepared by sol-gel method with various Nb mole ratios on Pt/ $SiO_2$/Si (100) substrates. The films were annealed at different temperatures and characterized in terms of phase and microstructure. Relatively a well saturated hysteresis pattern was obtained at x =0.2 in S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$)$_2$ $O_{9+}$$\alpha$/ thin films. At an applied voltage of 5V, the dielectric constant ($\varepsilon$$_{r}$) and dissipation factor (tan $\delta$) of typical S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$)$_2$ $O_{9+}$$\alpha$/ thin film (x=0.2) were about 236.2 and 0.034. Measured remanent polarization (2Pr) and coercive field (Ec) were 4.28C/c $m_2$, and 38.88kv/cm respectively. No fatigue was observed up to 6$\times$10$_{10}$ switching cycles at 5V and the normalized polarization reduced by a factor of only 4%.%. 4%.%. 4%.%.%.%.%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.12-13
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• 2006

Ferroelectric Cerium-substituted $Bi_4Ti_3O_{12}$ thin films with a thickness of 200 nm were deposited using the liquid delivery metal organic chemical vapor deposition process onto a Pt(111)/Ti/$SiO_2$/Si(100) substrate. At annealing temperature above $600^{\circ}C$, the BCT thin films became crystallized and exhibited a polycrystalline structure. The BCT thin film annealed at $720^{\circ}C$ showed a large remanent polarization ($2P_r$) of $44.56\;{\mu}C/cm^2$ at an applied voltage of 5V. The BCT thin film exhibits a good fatigue resistance up to $1{\times}10^{11}$ switching cycles at a frequency of 1 MHz with applied electric field of ${\pm}5\;V$.

• E2M - 전기 전자와 첨단 소재
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• 제9권8호
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• pp.836-850
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• 1996

In this study, we have analyzed structural analysis and measured ferroelectric characteristics of PZT thin films prepared by sol gel process with different sintering conditions and different Zr/Ti mot%. When the Zr mot% of PZT thin film was increased, it was found that the remanent. polarization and coercive field were decreased and increased, respectively. Also, the maxium dielectric constant of PZT(50/50) thin film was 786.8. We got double hysteresis(anti-fcrroelectric) curve from PbZrO$_{3}$ thin film. As heating rate goes up, pyrochlore phase of PZT thin film was decreased and dielectric and ferroelectric characteristics were improved. As a result of variation of sintering temperature and time 500.deg. C-800.deg. C and 5 sec.-8 hours, respectively, we got optimal sintering temperature and time. The optimium sintering temperature and time of conventional furnace method and rapid thermal processing method were 650.deg. C-700.deg. C for 30-60 minutes and 700.deg. C/20 seconds-2 minutes, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.213-216
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• 2001

Etching behaviors of ferroelectric YMn $O_3$ thin films were studied by an inductively coupled plasma (ICP). Etch characteristic on ferroelectric YMn $O_3$ thin film have been investigated in terms of etch rate, selectivity and etch profile. The maximum etch rate of YMn $O_3$ thin film is 300 $\AA$/min at Ar/C $l_2$ of 2/8, RF power of 800W, dc bias voltage of 200V, chamber pressure of 15mTorr and substrate temperature of 3$0^{\circ}C$. Addition of C $F_4$ gas decrease the etch rate of YMn $O_3$ thin film. From the results of XPS analysis, Y $F_{X}$ compunds were found on the surface of YMn $O_3$ thin film which is etched in Ar/C1/C $F_4$ plasma. The etch profile of YMn $O_3$ film is improved by addition of C $F_4$ gas into the Ar/C $l_2$ plasma. These results suggest that fluoride yttrium acts as a sidewall passivants which reduce the sticking coefficient of chlorine on YMn $O_3$.>.

• 한국전기전자재료학회논문지
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• 제30권2호
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• pp.126-132
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• 2017

The power conversion efficiency of organic polymer solar cells was enhanced by introducing a ferroelectric polymer layer at the interface between active layer and metal electrode. The power conversion efficiency was increased by 50% through the enhancement of the open circuit voltage. To investigate the role of the ferroelectric layer on the dissociation process of the excitons, non-radiative portion of the exciton decay was directly measured by using photoacoustic technique. The results show that the ferroelectric nature of the buffer layer does not play any roles on the dissociation process of the excitons, which indicates the efficiency enhancement is not due to the ferroelectricity of the buffer layer.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.191-194
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• 1999

Switching behaviour of the ferroelectric thin film and device characteristics of the MFSFET (Metal-Ferroelectric-Semiconductor FET) are simulated with taking into account the accumulation of oxygen vacancies near interface between the ferroelectric thin film and the bottom electrode caused by the progress of fatigue. We show net switching current decreases due fatigue in the switching model. It indicates that oxygen vacancy strongly suppresses polarization reversal. The difference of saturation drain current of the device before fatigue is shown by the dual threshold voltages in I$_{D}$-V$_{D}$ curve as 6㎃/$\textrm{cm}^2$ and decreases as much as 50% after fatigue. Our simulation model is expected to play an important role in estimation of the behavior of MFSFET device with various ferroelectric thin films.lms.

• 한국결정성장학회지
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• 제12권3호
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• pp.161-164
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• 2002

Polycrystalline and epitaxial heterostructure films of $La_{0.5}Sr_{0.5}CoO_{3}/Pb(Nb_{0.04}Zr_{0.28}Ti_{0.68})O_{3}/La_{0.5}Sr_{0.5}CoO_{3}$ (LSCO/PNZT/LSCO) capacitors were evaluated in terms of low voltage and high speed operation in high density memory, using TiN/Pt conducting barrier combination. Structural studies for a high density ferroelectric memory process flow, which requires the integration of conducting barrier layers to connect the drain of the pass-gate transistor to the bottom electrode of the ferroelectric stack, indicate complete phase purity (i.e. fully perovskite) in both epitaxial and polycrystalline materials. The polycrystalline capacitors show lower remnant polarization and coercive voltages. However, the retention, and high-speed characteristics are similar, indicating minimal influence of crystalline quality on the ferroelectric properties.

• ETRI Journal
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• 제27권6호
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• pp.677-684
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• 2005

A phased array antenna was fabricated using four-element ferroelectric phase shifters with a coplanar waveguide (CPW) transmission line structure based on a $Ba_{0.6}Sr_{0.4}TiO_3(BST)/MgO$ structure. Epitaxial BST films were deposited on MgO (001) substrates by pulsed laser deposition. To attain the large differential phase shift and small losses for a ferroelectric CPW phase shifter, an impedance-matching-part adding technique between the effective transmission line and connecting cable was used. The return loss and insertion loss for this techniqueadapted BST CPW device were improved with respect to those for a normal BST CPW device. For an X-band phased array antenna system consisting of ferroelectric BST CPW phase shifters, power divider, dc block, patch antenna, and programmed dc power, the steering beam could be tilted by $15^{\circ}$ in either direction.

• 한국재료학회지
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• 제10권12호
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• pp.807-811
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• 2000

MFISFET (Metal-ferroelectric-nsulator-semiconductor-field effect transistor)에의 적용을 위해 CeO$_2$와 SrBi$_2$Ta$_2$O$_{9}$ 박막을 각각 r.f. sputtering 및 pulsed laser ablation법으로 제조하였다. CeO$_2$ 박막은 증착시 스퍼터링개스비 (Ar:O$_2$)에 따른 특성을 고찰하였다. Si(100) 기판 위에 $700^{\circ}C$에서 증착된 CeO$_2$ 박막들은 (200)방향으로 우선방향성을 가지고 성장하였고 $O_2$ 개스량이 증가함에 따라 박막의 우선방향성, 결정립도 및 표면거칠기는 감소하였다. C-V특성에서는 Ar:O$_2$가 1 : 1인 조건에서 제조된 박막이 가장 양호한 특성을 보였다. 제조된 박막들의 누설전류값은 100kV/cm의 전계에서 $10^{-7}$ ~$10^{-8}$ A의 차수를 보였다. CeO$_2$/Si 기판위에 성장된 SBT는 다결정질상의 치밀한 구조를 가지고 성장을 하였다 80$0^{\circ}C$에서 열처리된 SBT박막으로 구성된 MFIS구조의 C-V 특성에서 memory window 폭은 0.9V를 보였으며 5V에서 4$\times$$10^{-7}$ A/$\textrm{cm}^2$의 누설전류밀도를 보였다.

• 한국산학기술학회논문지
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• 제16권3호
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• pp.2131-2134
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• 2015

본 논문에서는 종이를 기판으로 사용하고 용액공정이 가능한 강유전체 메모리 소자의 제작 가능성을 검토하였다. 유기물 강유전체인 "폴리비닐리덴트리플루오르에틸렌" 용액을 하부전극이 형성된 종이기판 위에 스핀코핑 방법을 이용하여 도포하였다. 하부전극으로는 진공증착법을 이용하여 알루미늄을 증착하였고, 도포된 "폴리비닐리덴트리플루오르에틸렌" 용액은 열처리 과정을 통해 결정화하였다. 제작된 "폴리비닐리덴트리플루오르에틸렌" 박막은 주사 전자 현미경법(SEM), 원자간력 현미경(AFM)을 이용하여 박막의 단면 및 표면의 특성을 평가하였다. 전압에 따른 분극특성 측정을 통해, 종이기판 위에 형성된 "폴리비닐리덴트리플루오르에틸렌" 박막이 매우 훌륭한 강유전체 특성을 보여주고 있음을 확인하였다. 또한, 종이기판의 응용가능성을 검토하기 위하여, 실리콘 기판위에 제작한 "폴리비닐리덴트리플루오르에틸렌" 박막과의 비교에 있어서도 손색없는 강유전체 특성을 보여주고 있음을 알 수 있었다. 이러한 결과들은 종이를 기판으로 이용하여 전자소자들을 제작 할 수 있음을 시사하며, 또한 용액공정으로 고밀도의 저렴한 강유전체 메모리 소자를 손쉽게 제작 할 수 있다는 것을 의미한다.