• Journal of the Korean Vacuum Society
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• v.17 no.6
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• pp.560-565
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• 2008

$(Pb_{0.98}La_{0.08})(Zr_{0.65}Ti_{0.35})O_3$ (PLZT) thin films with $TiO_2$ buffer layers were deposited on Pt/Ti/$SiO_2$/Si substrates by an R.F. magnetron sputtering method in order to improve the ferroelectric characteristics of the films. And the ferroelectric properties and crystallinities of the PLZT thin films were investigated in terms of the effects of the post annealing temperatures of $TiO_2$ buffer layers between a platinum bottom electrode and PLZT thin film. The ferroelectric properties of the PLZT thin films improved as increasing of the post annealing temperatures of $TiO_2$ layers, thereby reaching their maximum at $600^{\circ}C$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.986-991
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• 2016

In this study, we prepared ITO thin films on $Nb_2O_5/SiO_2$ double buffer layer using DC magnetron sputtering method and investigated electrical and optical properties with various substrate temperatures (room temperature ~ $400^{\circ}C$). The resistivity showed a decreasing tendency, because crystallinity has been improved due to the enlarged grain size with increasing substrate temperature. ITO thin film deposited at $400^{\circ}C$ showed the most excellent value of resistivity and sheet resistance as $3.03{\times}10^{-4}{\Omega}{\cdot}cm$, $86.6{\Omega}/sq.$, respectively. In results of optical properties, average transmittance was increased but chromaticity ($b^*$) was decreased in visible light region (400~800nm) with increasing substrate temperature. Average transmittance and chromaticity ($b^*$) of ITO thin film deposited at $400^{\circ}C$ exhibited significantly improved results as 85.8% and 2.13 compared to 82.8% and 4.56 of the ITO thin film without buffer layer. Finally, we found that ITO thin film introduced $Nb_2O_5/SiO_2$ double buffer layer has a remarkably improved optical property such as transmittance and chromaticity due to the index matching effect.

• Journal of the Korean Ceramic Society
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• v.36 no.10
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• pp.1087-1093
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• 1999

Bioglass which is one of the surface active bionmaterials has a good biocompatibility but a poor mechanical strength, In the present work therefore two types of fluoride-containing bioglasses were coated on an alumina to improve mechanical strength. Crystallization of the coating layer and the hydroxyapatite formation on the bioactive glass coatings in tris-buffer solution were studied. When bioactive glass coated alumina was heat-treated Na2CaSi3O8 crystal was formed on the layer at lower temperature while wollastonite(CaSIO3) was obtained at higher temperature. Hydroxyapatite forming rate on the coating layer with Na2CaSi3O8 crystal was delayed with SiO2 contents in glass composition. However the hydroxyapatite was developed in 20minutes regardless SiO2 contents when the coating layer crystallized into wollastonite. More amount of P3+ ions were leached out of the coating layer with wollastonite than that with Na2CaSi3O8 crystal while Na+ and Ca2+ ions were leached out more easily from the Na2CaSi3O8 crystal containing coating layer.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.307-314
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• 1998

PZT thin films were fabricated by the Sol-gel method. Starting materials used for the preparation of the stock solution were Pb-acetate trihydrate, Zr-normal propoxide and Ti-isopropoxide. 2-Methoxyethanol and iso-propanol were used for solution. For studying the diffusion of Pb ion into the substrates. We used bare Si substrate, $SiO_2/Si$ substrates which was produced by thermal oxidation and $TiO_2/SiO_2/Si$ which was mad by Sol-gel method. Densification and adhesion of thin films were observed by SEM. Phase formation of thin films and diffusion of Pb ion into the substrate were examined by XRD and ESCA, respectively. In the case of bare Si and $SiO_2/Si$ substrate, we obtained the perovskite phase at $700^{\circ}C$ and restricted a little the diffusion of Si ion into the film with $SiO_2$ buffer layer. In the case of $TiO_2/SiO_2/Si$, perovskite phase were obtained at $500^{\circ}C$ and the diffusion of Pb ion and Si ion were restriced.

• Journal of the Korean Ceramic Society
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• v.42 no.3 s.274
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• pp.178-181
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• 2005

Silicon oxynitride (SiON) layers deposited upon a $SiO_2/Si$ buffer layer placed upon silicon wafers have been obtained by using PECVD from $SiH_4,\;N_2O$, and $N_2$. It can be seen that the refractive index, measured by using a prism coupler, for the SiON films can be varied between 1.4480 and 1.4958 at a wavelength of 1552 nm by changing the process parameters. Optical planar waveguides with a thickness of $6{\mu}m$ and a refractive index contrast ($\Delta$n) of $0.36\% have been deposited. Also, etching experiments were performed using ICP dry etching equipment on thick SiON films grown onto Si substrates covered by a thick $SiO_2$ buffer layer. A polarization maintaining single-mode fiber was used for the input and a microscope objective for the output at $1.55{\mu}m$. As a result, a low index contrast SiON based waveguide is fabricated with easily adjustable refractive index of core layer. It illustrates that the output intensity mode is a waveguiding single-mode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.186-189
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• 2003

The MFIS capacitors were fabricated using a metalorganic decomposition method. Thin layers of $ZrO_2$ and $CeO_2$ were deposited as a buffer layer on Si substrate and BLT thin films were used as a ferroelectric layer. The electrical and structural properties of the MFIS structure were investigated. X -ray diffraction was used to determine the phase of the BLT thin films and the quality of the $ZrO_2$ and $CeO_2$ layer. AES show no interdiffusion and the formation of amorphous $SiO_2$ layer is suppressed by using the $ZrO_2$ and $CeO_2$ film as buffer layer between the BLT film and Si substrate. The width of the memory window in the C-V curves for the $BLT/ZrO_2/Si$ and $BLT/CeO_2/Si$ structure is 2.94 V and 1.3V, respectively. The experimental results show that the BLT-based MFIS structure is suitable for non-volatile memory FETs with large memory window.

• Journal of Ceramic Processing Research
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• v.13 no.spc2
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• pp.336-340
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• 2012

Wide band gap p-type hydrogenated amorphous silicon oxide (a-SiO:H) buffer layer has been used at the interface of transparent conductive oxide (TCO) and hydrogenated amorphous silicon (a-Si:H) p-type layer of a p-i-n type a-Si:H solar cell. Introduction of 5 nm thick buffer layer improves in blue response of the cell along with 0.5% enhancement of photovoltaic conversion efficiency (η). The cells with buffer layer show higher open circuit voltage (Voc), fill factor (FF), short circuit current density (Jsc) and improved blue response with respect to the cell without buffer layer.

• Journal of the Korean Ceramic Society
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• v.37 no.11
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• pp.1097-1104
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• 2000

MOD(Metal-Organic-Decomposition)법에 의해 $Y_2$O$_3$버퍼층에 Pt/TiO$_2$/SiO$_2$/Si 기판 위에 제조한 후, 그 표면 위에 졸-겔 방법으로 YMnO$_3$박막을 형성하였다. 기판의 종류와 수화조건 변화가 YMnO$_3$박막의 결정화 거동에 미치는 영향을 고찰하였으며, 또한 $Y_2$O$_3$버퍼층 유.무에 따른 Mn의 산화상태를 확인하고 이에 따른 유전특성 변화를 연구하였다. $Y_2$O$_3$버퍼층을 삽입하지 않고 직접 기판 위에 형성한 YMnO$_3$박막의 결정상은 기판의 종류 및 Rw 변화에 관계없이 orthorhombic 구조임이 확인되었다. 반면, $Y_2$O$_3$버퍼층 위에 형성된 YMnO$_3$박막의 경우에는 Rw($H_2O$/alkoxide mole ratio)가 0~6 범위 내에서 낮아질술고 hexagonal 결정상 성장에 유리하였으며, 또한 Pt(111)/TiO$_2$/SiO$_2$/Si 기판이 Ptd(200)/TiO$_2$/SiO$_2$/Si에 비하여 결정상 형성에 용이하였다. $Y_2$O$_3$버퍼층은 YMnO$_3$결정상 내에서 $Mn^{4+}$ 이온형성을 억제함으로써 누설전류밀도가 크게 감소되는 효과를 주었으며, 동시에 강유전 특성을 지닌 hexagonal 결정상 형성에 유리하게 작용하였다. 결론적으로, $Y_2$O$_3$는 Pt가 코팅된 Si 기판 위에 YMnO$_3$박막 제조시 그 강유전 특성을 향상시켜주는 우수한 버퍼층 재료임을 확인하였다.

• Korean Journal of Materials Research
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• v.17 no.2
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• pp.115-120
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• 2007

Polycrystalline silicon (poly-Si) thin film transistors (TFTs) might be fabricated on the mica substrate and transferred to a flexible plastic substrate because mica can be easily cleaved into a thin layer. To overcome the adhesion and stress problem between poly-Si film and mica substrate, a buffer layer consisting of $SiO_x/Ta/Ti$ three layers has been developed. The $SiO_x$ layer is for electrical isolation, the Ti layer is for adhesion of $SiO_{x}$ and mica. and Ta is for stress relief between $SiO_x$ and Ti. A TFT was fabricated on the mica substrate by a conventional Si process and was successfully transferred to a plastic substrate.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1646-1648
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• 2000

This paper investigated structural and electrical properties of $Y_{2}O_3$ as a buffer layer of sin91r transistor FRAM (ferroelectric RAM). $Y_{2}O_3$ buffer layers were deposited at a low substrate temperature below 400$^{\circ}C$ and then RTA (rapid thermal anneal) treated. Investigated parameters are substrate temperature, $O_2$ partial pressure, post- annealing temperature, and suppression of interfacial $SiO_2$ layer generation. for a well-fabricated sample, we achieved that leakage current density ($J_{leak}$) in the order of $10^{-7}A/cm2$, breakdown electric field ($E_{br}$) about 2 MV/cm for $Y_{2}O_3$ film. Capacitance versus voltage analysis illustrated dielectric constants of 7.47. We successfully achieved an interface state density of $Y_{2}O_3$/Si as low as $8.72{\times}10^{10}cm^{-2}eV^{-1}$. The low interface states were obtained from very low lattice mismatch less than 1.75%.