• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.190-191
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• 2006

We have investigated optical properties of Si/graded-$Si_{1-x}Ge_x$/Si heterostructures grown by reduced pressure chemical vapor deposition. Compared to standard condition using Si(100) substrate and growth temperature of $650^{\circ}C$, Si(111) resulted in low growth rate and high Ge mole fraction. Also samples grown at higher temperatures exhibited increased growth rate and reduced Ge mole fraction. The features regarding both substrate temperature and crystal orientation, representing high incorporation of silicon supplied from gas stream played as a key parameter, illustrate that reaction control were prevailed in this process growth condition. Using secondary ion mass spectroscopy and spectroscopic ellipsometry, microscopic changes in atomic components could be analyzed for Si/graded-$Si_{1-x}Ge_x$/Si heterostructures.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.8
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• pp.365-370
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• 2001

We have proposed and fabricated a new poly-Si TFT employing air-cavities at the edges of gate oxide in order to reduce the vertical electric field induced near the drain due to low dielectric constant of air. Air-cavity has been successfully fabricated by employing the wet etching of gate oxide and APCVD (Atmospheric pressure chemical vapor deposition) oxide deposition. Our experimental results show that the leakage current of the proposed TFT is considerably reduced by the factor of 10 and threshold voltage shift under high gate bias is also reduced because the carrier injection into gate insulator over the drain depletion region is suppressed.

• Korean Journal of Materials Research
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• v.18 no.10
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• pp.535-541
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• 2008

Growth behavior of InGaN/GaN self-assembled quantum dots (QDs) was investigated with respect to different growth parameters in low pressure metalorganic chemical vapor deposition. Locally formed examples of three dimensional InGaN islands were confirmed from the surface observation image with increasing indium source ratio and growth time. The InGaN/GaN QDs were formed in Stranski-Krastanow (SK) growth mode by the continuous supply of metalorganic (MO) sources, whereas they were formed in the Volmer-Weber (V-W) growth mode by the periodic interruption of the MO sources. High density InGaN QDs with $1{\sim}2nm$ height and $40{\sim}50nm$ diameter were formed by the S-K growth mode. Dome shape InGaN dots with $200{\sim}400nm$ diameter were formed by the V-W growth mode. InN content in InGaN QDs was estimated to be reduced with the increase of growth temperature. A strong peak between 420-460 nm (2.96-2.70 eV) was observed for the InGaN QDs grown by S-K growth mode in photoluminescence spectrum together with the GaN buffer layer peak at 362.2 nm (3.41 eV).

• Korean Journal of Materials Research
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• v.5 no.5
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• pp.568-574
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• 1995

We investigated the effects of B-doping on the growth mechanism of ZnO films. The B-doped ZnO films, which were widely applied for transparent conducting electrode, were deposited by plasma enhanced chemcial vapor depostion(PECVD) using diethylzinc(DEZ), No.sub 2/. and B$_{2}$H$_{6}$. The deposition conditions were a sbustrate temperature of 30$0^{\circ}C$, an rf power of 200, and a chamber pressure of 1 torr. At the given depostion condition, the growth rate of B-doped ZnO thin films was higher than that of undoped ones, but didn't change even with further increasing B$_{2}$H$_{6}$ flow rate and the interplanar distance between(0002) planes was reduced as B atoms substituted Zn sites.s.

• Journal of the Korean Ceramic Society
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• v.56 no.5
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• pp.453-460
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• 2019

To reduce residual pores of composites and obtain a dense matrix, SiC_f/SiC composites were fabricated by chemical vapor deposition (CVI) using SiC nanorods. SiC nanorods were uniformly grown in the thickness direction of the composite preform when the reaction pressure was maintained at 50 torr or 100 torr at 1,100℃. When SiC nanorods were grown, the densities of the composites were 2.57 ~ 2.65 g/㎤, higher than that of the composite density of 2.47 g/㎤ for non-growing of SiC nanorods under the same conditions; grown nanorods had uniform microstructure with reduced large pores between bundles. The flexural strength, fracture toughness and thermal conductivity (room temperature) of the SiC nanorod grown composites were 412 ~ 432 MPa, 13.79 ~ 14.94 MPa·m^1/2 and 11.51 ~11.89 W/m·K, which were increases of 30%, 25%, and 25% compared to the untreated composite, respectively.

• ETRI Journal
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• v.34 no.2
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• pp.226-234
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• 2012

The novelty of this study resides in the fabrication of stoichiometric and stress-reduced $Si_3N_4/SiO_2/Si_3N_4$ triple-layer membrane sieves. The membrane sieves were designed to be very flat and thin, mechanically stress-reduced, and stable in their electrical and chemical properties. All insulating materials are deposited stoichiometrically by a low-pressure chemical vapor deposition system. The membranes with a thickness of 0.4 ${\mu}m$ have pores with a diameter of about 1 ${\mu}m$. The device is fabricated on a 6" silicon wafer with the semiconductor processes. We utilized the membrane sieves for plasma separations from human whole blood. To enhance the separation ability of blood plasma, an agarose gel matrix was attached to the membrane sieves. We could separate about 1 ${\mu}L$ of blood plasma from 5 ${\mu}L$ of human whole blood. Our device can be used in the cell-based biosensors or analysis systems in analytical chemistry.

• Journal of the Korean institute of surface engineering
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• v.31 no.2
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• pp.109-116
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• 1998

Highly transparent conductive pure and fluorine-doped tin oxide(FT0, $SnO_2$ : F) films have been prepared by low pressure metal organic chemical vapor deposition (LP-MOCVD) from various mixtures of tetramethyitin(TMT) with oxygen or oxygen containing ozone. The properties of TO films have been changed with the variation of gases, flow rate, and substrate temperature. The nsing of oxygen containing ozone instead of pure oxygen, reduced substrate temperature by 100-$150^{\circ}C$ while maintaining same thickness. The films prepared by using ozone showed the resistivity in the range from $10^~2$ to $10^{~3}\Omega$cm, and the mobiiity from 10 to $14\textrm{cm}^2$/Vs. Fluorine-doped tin oxide films had properties such as the resistivity about $10^{-4}\Omega$cm, and the mobility from 14 to $19\textrm{cm}^2$/Vs.

• Journal of the Korean Ceramic Society
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• v.26 no.3
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• pp.381-389
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• 1989

Effects of annealing temperature, time, and atmospehre on the flow characteristics of Atmospheric Pressure Chemical Vapor Deposition-borophosphosilicate glass were investigated. Stable step coverage can be obtained by annealing the BPSG film at 90$0^{\circ}C$ for 30 minutes in N2 atmosphere, but further heat treatment isnot effective. Flow characteristics of the BPSG film was better in steam atmosphere than in N2 atmosphere, and the factors which cause it were analyzed. The concentration of boron in the BPSG film was measured pretty accurately by FTIR spectrum. Boron content in the BPSG film was reduced by annealing treatment. The decrement of boron was greater in steam atmosphere than in the N2 atmosphere. Also it was found from the FTIR spectroscopic analysis that PH3 inhibited the oxidation of B2H6.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.8
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• pp.657-662
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• 2003

This paper presents a new fabrication method of selective SiGe epitaxial growth at 650 $^{\circ}C$ on (100) silicon wafer with oxide patterns by reduced pressure chemical vapor deposition. The new method is characterized by a cyclic process, which is composed of two parts: initially, selective SiGe epitaxy layer is grown on exposed bare silicon during a short incubation time by SiH$_4$/GeH$_4$/HCl/H$_2$system and followed etching step is achieved to remove the SiGe nuclei on oxide by HCl/H$_2$system without source gas flow. As a result, we noted that the addition of HCl serves not only to reduce the growth rate on bare Si, but also to suppress the nucleation on SiO$_2$. In addition, we confirmed that the incubation period is regenerated after etching step, so it is possible to grow thick SiGe epitaxial layer sustaining the selectivity. The effect of the addition of HCl and dopants incorporation was investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.6
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• pp.580-585
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• 2004

Silicon dioxide (SiO$_2$) is widely used as a gate dielectric material for thin film transistors (TFT) and semiconductor devices. In this paper, SiO$_2$ films were grown by APCVD(Atmospheric Pressure chemical vapor deposition) at the high temperature. Experimental investigations were carried out as a function of $O_2$ gas flow ratios from 0 to 200 1pm. This article presents the SiO$_2$ gate dielectric studies in terms of deposition rate, refrative index, FT-IR, C-V for the gate dielectric layer of thin film transistor applications. We also study defect passivation technique for improvement interface or surface properties in thin films. Our passivation technique is Forming Gas Annealing treatment. FGA acts passivation of interface and surface impurity or defects in SiO$_2$ film. We used RTP system for FGA and gained results that reduced surface fixed charge and trap density of midgap value.