• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1598-1600
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• 2003

Microcrystalline silicon(c-Si:H) thin-film solar cells are prepared with intrinsic Si-layer by hot wire CVD. The operating parameters of solar cells are strongly affected by the filament temperature ($T_f$) during intrinsic layer. Jsc and efficiency abruptly decreases with elevated $T_f$ to $1400^{\circ}C$. This deterioration of solar cell parameters are resulted from increase of crystalline volume fraction and corresponding defect density at high $T_f$ The heater temperature ($T_h$) are also critical parameter that controls device operations. Solar cells prepared at low $T_h$ (<$200^{\circ}C$) shows a similar operating properties with devices prepared at high $T_f$, i.e. low Jsc, Voc and efficiency. The origins for this result, however, are different with that of inferior device performances at high $T_f$. In addition the phase transition of the silicon films occurs at different silane concentration (SC) by varying filament temperature, by which highest efficiency with SC vanes with $T_f$.

• Journal of Radiation Protection and Research
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• v.26 no.1
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• pp.7-12
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• 2001

Sintered LiF:Mg,Cu,Na,Si thermoluminescence (TL) pellets were developed for application in radiation dosimetry. In the present study, the TL dosimetric properties of LiF:Mg,Cu,Na,Si TL pellets have been investigated for emission spectrum, dose response, energy response, and fading characteristics. LiF:Mg,Cu,Na,Si TL pellets were made by using a sintering process, that is, pressing and heat treatment from TL powders. Photon irradiations for the experiments were carried out using X-ray beams and a $^{137}Cs$ gamma source at the Korea Atomic Energy Research Institute (KAERI). The average energies and the dose were in the range of 20-662 keV and $10^{-6}-10^{-2}\;Gy$, respectively. The glow curves were measured with a manual type TLD reader(System 310, Teledyne) at a constant nitrogen flux and a linear heating rate. For a constant heating rate of $5^{\circ}C\;s^{-1}$, the main dosimetric peak of glow curve appeared at $234^{\circ}C$, the activation energy was 2.34 eV and frequency factor was $1.00{\times}10^{23}$. TL emission spectrum is appeared at the blue region centered at 410 nm. A linearity of photon dose response was maintained up to 100 Gy. The photon energy responses relative to $^{137}Cs$ response were within ${\pm}20%$ at overall photon energy region. The fading of TL sensitivity of the pellets stored at the room temperature was not found for one year.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.18-21
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• 1995

In this study, crystallization, water swelling and dielectric properties of Li$_2$O-MgO-MgF$_2$-SiO$_2$System glass ceramics were investigated. Base glass melted at 1450$^{\circ}C$ and crystallized through heat treatment. The optimum heat treatment schedule was 460$^{\circ}C$ for nucleation and 640$^{\circ}C$, 1100$^{\circ}C$ for crystallization. The Principle crystalline phase was lithium fluorhectorite. Lithium fluorhectorite was the crystal phase which it was influenced water swelling. Samples progressed 2 minutes later they have rapid hydration at forced water swelling condition. Also value of dielectric constants have approximately 10 at 100kHz.

• Electrical & Electronic Materials
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• v.10 no.10
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• pp.1029-1033
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• 1997

A prototype MFSFET using ferroelectric fluoride BaMgF$_4$as a gate insulator has been successfully fabricated with the help of 2 sheets of metal mask. The fluoride film was deposited in an ultrai-high vacuum system at a substrate temperature of below 30$0^{\circ}C$ and an in-situ post-deposition annealing was conducted for 20 seconds at $650^{\circ}C$ in the same chamber. The interface state density of the BaMgF$_4$/Si(100) interface calculated by a MFS capacitor fabricated on the same wafer was about 8$\times$10$^{10}$ /cm$^2$.eV. The I$_{D}$-V$_{G}$ characteristics of the MFSFET show a hysteresis loop due to the ferroelectric nature of the BaMgF$_4$film. It is also demonstrated that the I$_{D}$ can be controlled by the “write” plus which was applied before the measurements even at the same “read”gate voltage.ltage.

• Korean Journal of Materials Research
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• v.7 no.8
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• pp.635-639
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• 1997

ECR-PECVD법을 사용하여 450-49$0^{\circ}C$이하의 온도에서 Pt/SiO$_{2}$/Si기판 위에 PZT 박막을 증착하였다. 기판 온도가 46$0^{\circ}C$ 이하일 경우에는 페로브스이트 상과 제2상으로 이루어진 박막이 성장하였으며 기판온도가 47$0^{\circ}C$이상일 때에는 페로브스카이트 단일상의 PZT 박막이 성장하였다. 49$0^{\circ}C$에서 매우 얇은 페로브스카이트의 PZT 박막을 증착한 후 $650^{\circ}C$에서 1분간 raped thermal annealing(RTA) 처리한 결과 박막의 조성과 결정성에는 거의 변화가 없었으나 박막의 전하 저장 밀도는 크게 향상되었다. 이는 RTA 처리에 의한 저유전 계면층의 소멸이 주된 이유라고 판단된다. 열처리 후 두께 40-45nm의 PZT박막은 200kV/cm의 전장 하에서 $10^{-6}$$\textrm{cm}^2$이하의 누설전류값을 갖고 있었으며, 인가전압 1V에서 300fF/$\mu$$m^2$의 정전용량, 즉 SiO$_{2}$환산두께 0.12nm를 나타내었다.

• Bulletin of the Korean Chemical Society
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• v.20 no.4
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• pp.427-430
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• 1999

The Grignard coupling reaction of bis(chloromethyl)diorganosilanes [(ClCH2)2SiR1R2: R1 = R2 = Me, la; R1 = Me, R2 = Ph, lb; R1 = R2 = Ph, lc] with diorganodichlorosilanes [(Cl2SiR3R4: R3 = R4 = Me, 2a; R3 = Me, R4 = Ph, 2b; R3 = R4 = Ph, 2c] at THE reflux temperature gave the intermolecular C-Si coupling product of 1,1,3,3-tetraorgano-1,3-disilacyclobutanes 3a-f in poor to moderate yields ranging from 7% to 50% along with polydiorganosilapropanes. The cyclization reaction of la-c with methyl-substituted dichlorosilanes 2a, b gave 1,3-disilacyclobutanes 3a-c, e, d in moderate yields (42-50%), while the same reaction with dichlorodiphenylsilane (2c) to 1,3-disilacyclobutanes 3d, f resulted in low yield (7-18%) probably due to the steric hindrance of two-phenyl groups on the silicon of 2c.

• Journal of Korean Vacuum Science & Technology
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• v.7 no.2
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• pp.33-38
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• 2003

Fluorinated amorphous carbon thin films (a-C:F) for the use of low dielectric constant intermetallic layer dielectrics are deposited by plasma enhanced chemical vapor deposition with $C_4$F$_{8}$ and Si$_2$H$_{6}$/He gas mixture as precursors. To characterize and improve film properties, we changed various conditions such as deposition temperature, and RF power, and we measured the thickness and refractive indexes and FT-IR spectrum before and after annealing. At low temperatures the film properties were very poor although the growth rate was very high. On the other hand, the growth rate was low at high temperature. The growth rate increased in accordance with the deposition pressure. The dielectric constants of samples were in the range of 1.5∼5.5∼5.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.64-68
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• 1995

Silicon films were deposited at $430^{\circ}C$ by remote plasma chemical vapor deposition(RPECVD) with a gas mixture of $Si_2H_6/SiF_4/H_2$. The silicon films deposited without and with $SiF_4$ were characterized using atomic force microscopy(AFM), transmission electron microscopy(TEM) and X-ray diffraction(XRD). Both silicon films have the same rugged surface morphology, but, the silicon film deposited with $SiF_4$ exhibits more rugged. The silicon film deposited without $SiF_4$ is amorphous, whereas the silicon film deposited with $SiF_4$ is polycrystalline with very small needle-like grains which are perpendicular to the substrate and uniformly distributed in the thickness of the film. The silicon film deposited with $SiF_4$ was found to have a preferred orientation along the growth direction with the<110> of the film parallel to the <111> of the substrate. The effect of $SiF_4$ during RPECVD was discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.101-105
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• 2024

4H-SiC power metal-oxide-semiconductor field effect transistors (MOSFETs) have been developed to achieve lower specific-on-resistance (R_on,sp), and the gate oxides have been thermally grown. The poor channel mobility resulting from the high interface trap density (D_it) at the SiO₂/4H-SiC interface significantly affects the higher switching loss of the power device. Therefore, the development of novel fabrication processes to enhance the quality of the SiO₂/4H-SiC interface is required. In this paper, NO post-oxidation annealing (POA) by using the conditions of N₂ diluted NO at a high temperature (1,300℃) is proposed to reduce the high interface trap density resulting from thermal oxidation. The NO POA is carried out in various NO ambient (0, 10, 50, and 100% NO mixed with 100, 90, 50, and 0% of high purity N₂ gas to achieve the optimized condition while maintaining a high temperature (1,300℃). To confirm the optimized condition of the NO POA, measuring capacitance-voltage (C-V) and current-voltage (I-V), and time-of-flight secondary-ion mass spectrometry (ToF-SIMS) are employed. It is confirmed that the POA condition of 50% NO at 1,300℃ facilitates the equilibrium state of both the oxidation and nitridation at the SiO₂/4H-SiC interface, thereby reducing the D_it.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1592-1594
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• 2003

This paper presents the deposition and characterization of microcrystalline silicon(${\mu}c$-Si:H) films by HWCVD(Hot-wire Chemical Vapor Deposition) method at low substrate($300^{\circ}C$). The filament temperature, pressure and $SiH_4$ concentration were determined to be a critical parameter for the deposition of poly-Si films. Series A was deposited under the conditions of $1380^{\circ}C$(Tf), 100 mTorr and $2{\sim}10%\{SC:SiH_4/(SiH_4+H_2)\}$ for 60 min. Series B was deposited under the conditions of $1400{\sim}1450^{\circ}(T_f)$, 30 mTorr and $2{\sim}12%$(SC) for 60 min. The physical characteristics were measured by Raman and FTIR spectroscopy, dark and photoconductivity measurements under AM1.5 illumination.