• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.377-380
• /
• 2001

The BST thin films to composite (Ba$\sub$x/Sr$\sub$l-x/)TiO$_3$ using sol-gel method were fabricated on Pt/Ti/SiO$_2$/Si substrate. The thin film capacitor to be ferroelectric materials was investigated by structural and electrical properties. BST solution was composited by moi ratio, and then spin-coated (from 3 times to 5 times coating on Pt/SiO$_2$/Si substrate. Thickness of BST ceramics thin films are about 2600∼2800[${\AA}$] in 3 times deposition. The property of leakage current was stable when the applied voltage was 3[V]. Leakage current of 3 times coated BST thin film was 10$\^$-9/∼10$\^$-11/[A] at 0∼3[V].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.11a
• /
• pp.85-86
• /
• 2007

A poly(vinylidene fluoride-trifluoroethyene) (P(VDF-TrFE)) copolymer thin film having ${\beta}$ phase was prepared by sol-gel method. The electrical properties of the film were studied to evaluate the possibility for appling to a ferroelectric random access memory. In order to characterize its electrical properties, we produced a MFS (metal-ferroelectric-semiconductor) structure by evaporation of Au electrodes. The C-V (capacitance-voltage) measurement revealed that the Au/P(VDF-TrFE)/Si structure with a 4 wt% film had a memory window width of about 0.5V for a bias voltage sweep of 1V.

• Korean Journal of Materials Research
• /
• v.19 no.4
• /
• pp.228-231
• /
• 2009

Phase transition in ferroelectric polymer is very interesting behavior and has been widely studied for real device applications, such as actuators and sensors. Through the phase transition, there is structural change resulting in the change of electrical and optical properties. In this study, we fabricated the Febry-Perot interferometer with the thin film of ferroelectric P(VDF-TrFE) 50/50 mol% copolymer, and thermo-optical properties were investigated. The effective thermo-optical coefficient of P(VDF-TrFE) was obtained as $2.3{\sim}3.8{\times}10^{-4}/K$ in the ferroelectric temperature region ($45^{\circ}C{\sim}65^{\circ}C$) and $6.0{\times}10^{-4}/K$ in the phase transition temperature region ($65^{\circ}C{\sim}85^{\circ}C$), which is a larger than optical silica-fiber and PMMA. The resonance transmission peak of P(VDF-TrFE) with the variation of temperature showed hysteretic variation and the phase transition temperature of the polymer in heating condition was higher than in the cooling condition. The elimination of the hysteretic phase transition of P(VDF-TrFE) is necessary for practical applications of optical devices.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.2 no.3
• /
• pp.213-225
• /
• 2002

Metal-Ferroelectric- Insulator- Silicon (MFIS) structured field effect transistor (FET) device was fabricated and characterized. Important issues to realize ferroelectric gate field effect transistor device were summarized in three sections. The choice of interlayer dielectric was made in the consideration of device functionality and chemical reaction between ferroelectric materials and silicon surface during fabrication process. Also, various ferroelectric thin film materials were taken into account to meet desired memory window and process compatibility. Finally, MFIS structured FET device was fabricated and important characteristics were discussed. For feasible integration of current device as random access memory array cell address schemes were also suggested.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.12-13
• /
• 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 ${\pm}5\;V$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.366-367
• /
• 2006

Different orientated SBN thin films were deposited by Ion Beam Sputtering, and electric properties were measured on each orientation. Ferroelectric $Sr_xBa_{1-x}Nb_2O_6$(SBN) has excellent electro-optic, photo-refractive, piezoelectric, pyroelectric properties. SBN thin film has been deposited by various method, of sol-gel, PLD, CVD, sputtering, etc.. To avoid lead pollution of Pb-system perovskite ferroelectric materials. SBN thin films were fabricated for pyroelectric IR sensor. Using the ceramic target of the same composition and Pt(100)/$TiO_2/SiO-2$/Si(100) substrate, crystallization and orientation behavior as well as electric properties of the films were examined. Seed layer and thin films thickness was controlled to observe the effect on preferred orientation. We measured I-V, C-V, P-E hysteresis to characterize electric-properties on each orientations.

• Electrical & Electronic Materials
• /
• v.9 no.2
• /
• pp.132-137
• /
• 1996

Pb(Zr$_{x}$Ti$_{1-x}$ )O$_{3}$ solutions prepared by sol-gel processing with different Zr/Ti ratio were coated on Pt/SiO$_{2}$/Si substrates using spin coating method. Coated films were annealed by rapid thermal annealing at 650.deg. C for 20sec to fabricate Pb(Zr, Ti)O$_{3}$ ferroelectric thin films. Electrical properties of the films such as dielectric constant and loss, ferroelectric hysteresis, fatigue, switching time, and leakage current were measured. Hysteresis of the films with different Zr/Ti ratio yield Pr ranging 10-21.mu.C/cm$^{2}$, E$_{c}$ ranging 37.5-137.5kV/cm. Hysteresis curve was changed from square-type to slim type according to increasing Zr contents. Switching time was faster than 180ns, and leakage current was about 20.mu.A/cm$^{2}$. The film underwent above 10$^{8}$ cycles of reversed polarization showed fatigue with increased coercive field and decreased remnant polarization.tion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07b
• /
• pp.861-864
• /
• 2002

Ferroelectric $Bi_{4-x}Nd_xTi_3O_{12}$(BNdT) thin films with the composition(x=0.75) were prepared on pt/Ti/$SiO_2$/Si(100) substrate by metal-organic deposition. The electrical and structural characteristics of BNdT thin films were investigated to develop ferroelectric thin films for capacitor layers of FRAM. After spin coating, thin films were annealed at $650^{\circ}C$ for 1hour in oxygen atmosphere. Scanning electron micrographs showed uniform surfaces composed of rod-like grains. The $Bi_{4-x}Nd_xTi_3O_{12}$(X=0.75) thin film capacitors with a Pt top electrode showed better ferroelectric properties. At the applied voltage of 5V, the dielectric constant$(\varepsilon_r)$, dissipation factor$(tan{\delta})$, remanent polarization(2Pr) and nonvolatile swiching charge of the $Bi_{4-x}Nd_xTi_3O_{12}$(x=0.75)thin films were about 346.7, 0.095, $56{\mu}C/cm^2$ and $38{\mu}C/cm^2$ respectively. Also the capacitor did not show any significant fatigue up to $8{\times}10^{10}$ read/write switching cycles at a frequency of 1MHz.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.11a
• /
• pp.142-142
• /
• 2003

The effects of film thickness on the dipolar relaxation of ferroelectric PbTiO$_3$ films were investigated in the microwave-frequency range. The dielectric constants ($\varepsilon$) and the dielectric losses (tan $\delta$) were successfully measured up to 30 ㎓ using interdigital capacitors. The PbTiO$_3$ thin films were deposited on the quartz substrate at room temperature and postannealed in oxygen atmosphere. As the film thickness increased, its grain size and tetragonality were enhanced. And the dipolar relaxation behavior began to appear in the thin films with approximately 20 nm thickness, since ferroelectric domains could not be formed hi small grains. The observed relaxation frequency (above 10 ㎓) was higher than the previous values reported in bulk ceramics. It can be correlated with the extremely small domain size of the thinfilms as shown by TEM. And, the Rayleigh constant [1] from domain wall motions was alsoinvestigated by LCR meter at 100 KHz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.717-720
• /
• 2001

Ferroelectric lead ziroconate titanate (PZT) thin film were fabricated on the different bottom electrodes. Both Ru and Ru/RuO$_2$bottom electrodes were deposited by RF-magnetron sputteirng method. The structure phase and surface morphology of the PZT thin film were largely affected by the bottom electrode. It was observerd that used of Ru/RuO$_2$double electrode reduced leakage current and better ferroelectric properties compare with RuO$_2$bottom electrode. From these results, Ru/RuO$_2$hybride bottom electrode is thought to be the available structure for the bottom electrode.