• 한국기계가공학회지
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• 제16권5호
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• pp.63-68
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• 2017

This study determines the selection of an appropriate jig material for the blade edge of the medical sapphire knife. The physical properties of the jig material affects the edge shape and chipping phenomenon in machining of the medical sapphire knife. If a grinding wheel is used, brittle workpieces such as sapphire are easily damaged by the propagation of cracks because the grinding force significantly increases. It is important to constantly maintain the grinding force in the grinding process of the brittle materials. The grinding force can be kept constantly by inducing the elastic deformation of the Jig material because the elastic deformation of brittle work-piece is negligibly low. The chipping phenomenon may be reduced by selecting the proper Jig material. Aluminum, copper, stainless steels and carbon steel were used as Jig materials. The experiment was conducted using a cast iron grinding wheel, which was installed on a conventional grinding machine with the ELID grinding system. The thickness and width of the chipping area were measured using an optical microscope and FE-SEM to analyze the shape of the blade edge. According to the experiment result, the chipping phenomenon decreased, and the sharp edge was formed when the jig materials with low elastic modulus were used.

• 한국결정학회지
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• 제1권2호
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• pp.99-104
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• 1990

본 연구에서는 고밀도 광원 활용에 의한 유기금속화합물의 광분해 반응을 이용하여 AmBv 형광 전재료의 Hetero-epitaxy를 고찰하였다. 실제로 ArF Excimer laser(파장 193nm)에 의 하여 III족원으로 trlmethylgallium과 V족원으로 Ammonia의 2분자간 광분해 반응을 이용, (001)면 Sapphire 기판상에 증착시켰다. 생성되는 성막상태는 주사식 전자현미경, X-ray 회절 및 전자선 회절법 (RED)에 의하여 평가하였다. Laser광려기 유무에 따라 결정병합 상태 및 결정형태에 현저한 차이를 관찰할 수 있었으며, 특히 결정격자의 방위성에 큰 영향을 주고 있음이 주목되었다. 광원 조사방법은 수직조사에 의한 기판면 여기보다는 수평조사에 의 한 기상 반응물 여기가 더 효과적 이였다. Laser 광여기에 의한 성막층의 격자형성은 다음 과 같은 2가지 Model중 하나로 설명 할 수 있었다. (001)면 Sapphire//wurzite형 GaN의 (001) 면 또는 (001)면 Sapphire//wurzite형 GaN인의 (001) 면 -t Twinned Zincblende형의 GaN(111)면

• 한국진공학회지
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• 제7권4호
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• pp.320-327
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• 1998

원격 플라즈마 화학기상증착법(Remote Plasma Enhanced-Ultrahigh Vacuum Chemical Vapor Deposition)에 의해 활성화된 질소 원자를 사용하여 사파이어 기판의 표면 을 저온에서 질화처리한 후 표면의 화학적 조성을 조사하였다. 질화처리에 의해 주로 표면 에 형성된 물질은 AIN임을 X-선 광전자 분광방법(X-ray photoelectron spectroscopy:XPS) 을 사용하여 확인하였다. 또한 플라즈마의 RF 출력, 반응 온도 및 시간에 따라서 기판의 Al 과 반응한 질소의 상대적인 양과, 표면 형태를 XPS와 AFM(atomic force microscopy)을 사 용하여 조사하였다. 플라즈마에 의해서 질소는 RF출력에 따라 증가한 후 일정하게 됨을 관 찰하였다. 그러나 질화 처리 온도와 시간의 증가에 따른 AIN의 상대적인 양은 비교적 무관 함을 관찰하였다. 또한 Ar스퍼터링을 통한 XPS의 depth profile을 관찰한 결과 질화층은 깊 이에 따라 3개의 다른 층으로 이루어져 있음을 확인하였다.

• 한국전기전자재료학회논문지
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• 제29권9호
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• pp.546-551
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• 2016

$SrSnO_3:Tb^{3+}$ phosphor thin films were prepared on sapphire and quartz substrates in the growth temperature range of $100{\sim}400^{\circ}C$ by using the radio frequency magnetron sputtering deposition. The resulting $SrSnO_3:Tb^{3+}$ thin films were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible-infrared spectrophotometer, and photoluminescence spectrometer. The results indicated that the morphology, optical transmittance, band gap energy, and luminescence intensity of the phosphor thin films significantly depended on the growth temperature. All the thin films, regardless of the type of substrate, showed an amorphous behavior. As for the thin films deposited on sapphire substrate, the maximum crystallite size was obtained at a growth temperature of $400^{\circ}C$ and the strongest emission was green at 544 nm arising from the $^5D_4{\rightarrow}^7F_5$ transition of Tb3+. The average optical transmittance for all the thin films grown on sapphire and quartz substrates was decreased as the growth temperature increased from 100 to $400^{\circ}C$. The results suggest that the optimum growth temperatures for depositing highly-luminescent $SrSnO_3:Tb^{3+}$ phosphor thin films on sapphire and quartz substrates are 400 and $300^{\circ}C$, respectively.

• Journal of the Optical Society of Korea
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• 제7권3호
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• pp.135-138
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• 2003

A chirped-pulse amplification femtosecond Ti:sapphire laser operating at 1 KHz has been developed. The laser system consisted of a long-cavity femtosecond oscillator, a four-pass grating pulse stretcher, two multi-pass amplifiers and a double-pass grating pulse compressor. Thermal lensing at the amplifiers was reduced by cooling Ti:sapphire crystals using Peltier coolers. Gain narrowing and residual phase errors were compensated for by the use of an acousto-optic pulse shaper. The final laser output had an energy per pulse of 2.0 mJ and a pulse duration of 19.5 fs, reaching 0.1 TW at 1 KHz.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.27.1-27.1
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• 2009

In recent years, ZnO nanostructures have drawn considerable attentions for the development of futuristic electronic devices due to their superior structural and optical properties. As the growth of ZnO nanowires by MOCVD is a bottom-up technique, the nature of substrates has a vital role for the dimension and alignment of the nanowires. However, in the pursuit of next generation ZnO based nanodevices, it would be highly preferred if well-ordered ZnO nanowires could be obtained on various substrates like sapphire, silicon, glass etc. Vertically aligned nanowires were grown on A and C-plane sapphire substrates, where as nanopencils were obtained on R-plane sapphire substrates. In addition, C-axis oriented vertical nanowires were also found using an interfacial layer(aluminum nitride film) on silicon substrates. On the other hand, long nanowires were found on Ga-doped ZnO film on glass substrates. Structural and optical properties of the ZnO nanowires on various substrates were also investigated.

• 한국전기전자재료학회논문지
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• 제19권10호
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• pp.923-929
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• 2006

Single crystalline ZnO films were successfully grown on R-plane sapphire substrates by plasma-assisted molecular beam epitaxy. Epitaxial relationship between the ZnO film and the R-plane sapphire was determined to be $[-1101]Al_2O_3{\parallel}[0001]ZnO,\;[11-20]Al_2O_2{\parallel}[-1100]ZnO$ based on the in-situ reflection high-energy electron diffraction analysis and confirmed again by high-resolution X-ray diffraction measurements. Grown (11-20) ZnO films surface showed mound-like morphology along the <0001>ZnO direction and the RMS roughness was about 4 nm for $2{\mu}m{\times}2{\mu}m$ area.

• 한국결정성장학회지
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• 제4권1호
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• pp.42-45
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• 1994

금 비스무스 용매를 사용하여 실리콘 박막을 사파이어, 보로실리케이트 그라스 기판상에 성장시켰다. 사파이어의 경우 $380~460^{\cire}C$ 에서 14 $\mu\textrm{m}$ 두께의 실리콘막이 성장되었으며, 그라스 기판의 경우 $420~520^{\circ}C$ 온도 범위에서 수백 $\mu\textrm{m}$ 사이즈의 큰 결정립이 형성되었다. 이결과는 저가의 박막태양전지를 제조하는데 응용될 것으로 사료된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.119-122
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• 2001

ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition(PLD) technique at the oxygen pressure of 350 mTorr. In order to investigate the effect of post-annealing treatment with oxygenn pressure of 350 mTorr on the optical property of ZnO thin films, films have been annealed at various substrate temperatures after deposition. After post-annealing treatment in the oxygen ambient, the optical properties of the ZnO thin films were characterized by PL(Photoluminescence) and structural properties of the ZnO were characterized by XRD, and have investigated structural property and optical property for application of light emission device.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.224-227
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• 2001

ZnO buffer layers were used to grow ZnO films on c-plane sapphire substrates. The role of ZnO buffer layers in the growth of ZnO thin films on sapphire substrates was investigated by scanning electron microscopy, X-ray diffraction, and Photolumminescence(PL) measurements. At the optimized ZnO buffer layer thickness of 100 $\AA$, FWHM of $\theta$ -rocking curve of ZnO thin films was minimized to 0.73 degrees and room temperature PL spectra showed that deep level emission was not hardly seen. The optimization of the ZnO buffer layer thickness resulted in improvements of the surface morphology and crystalline quality of ZnO thin films.