• 제목/요약/키워드: Laser Chemical Vapor Deposition

검색결과 123건 처리시간 0.024초

탄소 음이온 빔에 의해 증착된 DLC 필름의 특성 평가

  • 김인교;김용환;이덕연;최동준;한동원;백홍구
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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    • pp.59-59
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    • 1999
  • DLC(diamond-like carbon)필름은 다이아몬드와 유사한 강도, 낮은 마차계수, 높은 Optical band gap, NEA(negative electron affinity)등의 우수한 특성을 가지고 있어, 내마모 코팅이나 정보저장 매체의 윤활 코팅, FED(field emission display)의 전계방출소자등 다양한 분야에의 응용이 연구되고 있다. DLC 필름은 PECVD(plasma enhanced chemical vapor deposition), IBAD(ion beam assisted deposition), Laser ablation, Cathodic vacuum arc등의 process를 이용하여 증착되고 있다. 특히 이러한 필름의 물성은 입사되는 이온의 에너지에 의해 좌우되는데, Lifshitz 등의 연구에 의하여 hyperthermal species를 이용한 DLC 필름의 성장은 초기에 subsurface로의 shallow implantation이 일어난 후 높은 sp3 fraction을 갖는 필름이 연속적으로 성장한다는 subplantation model이 제시 되었다. 본 연구에서는 기판과 subplantation 영역이 이후 계속하여 증착되는 순수 DLC 필름의 특성 변호에 미치는 영향에 대하여 관심을 가지고 실험을 행하였다. 본 실험에서는 상기 제시되어 있는 방법보다도 더욱 정확하고도 독립적으로 탄소 음이온의 에너지와 flux를 조절할 수 있는 Cs+ ion beam sputtering system을 이용하여 탄소 음이온의 에너지를 40eV에서 200eV까지 변화시키며 필름을 증착하였다. Si(100) 웨이퍼를 기판으로 사용하였고 증착 압력은 5$\times$10-7torr 였으며 인위적인 기판의 가열은 하지 않았다. 또한 Ion beam deposited DLC film의 growth process를 연구하기 위하여 200eV의 탄소 음이온을 시간(증착두께)을 변수로 하여 증착하였고, 이 때에는 Kaufman type의 gas ion beam을 이용하여 500eV의 Ar+ ion으로 pre-sputering을 행하였다. 탄소 음이온의 에너지와 증착두께에 따라 증착된 film 내의 sp3/sp2 ratio 의 변화를 XPS plasmon loss 와 Raman spectra를 이용하여 분석하였다. 또한 증착두께에 따른 interlayer의 결합상태를 관찰하기 위하여 AES와 XPS 분석을 보조로 행하였다.

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A possibility of enhancing Jc in MgB2 film grown on metallic hastelloy tape with the use of SiC buffer layer

  • Putri, W.B.K.;Kang, B.;Ranot, M.;Lee, J.H.;Kang, W.N.
    • 한국초전도ㆍ저온공학회논문지
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    • 제16권2호
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    • pp.20-23
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    • 2014
  • We have grown $MgB_2$ on SiC buffer layer by using metallic Hastelloy tape as the substrate. Hastelloy tape was chosen for its potential practical applications, mainly in the power cable industry. SiC buffer layers were deposited on Hastelloy tapes at 400, 500, and $600^{\circ}C$ by using a pulsed laser deposition method, and then by using a hybrid physical-chemical vapor deposition technique, $MgB_2$ films were grown on the three different SiC buffer layers. An enhancement of critical current density values were noticed in the $MgB_2$ films on SiC/Hastelloy deposited at 500 and $600^{\circ}C$. From the surface analysis, smaller and denser grains of $MgB_2$ tapes are likely to cause this enhancement. This result infers that the addition of SiC buffer layers may contribute to the improvement of superconducting properties of $MgB_2$ tapes.

Inspection of Ceramic Coatings Using Nanoindentation and Frequency Domain Photoacoustic Microscopy

  • Steen, T.L.;Basu, S.N.;Sarin, V.K.;Murray, T.W.
    • 비파괴검사학회지
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    • 제26권6호
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    • pp.390-402
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    • 2006
  • The elastic properties and thickness of mullite environmental barrier coatings grown through chemical vapor deposition (CVD) on silicon carbide substrates were measured using frequency domain photoacoustic microscopy. In this technique, extremely narrow bandwidth surface acoustic waves are generated with an amplitude modulated laser source. A photorefractive crystal based interferometer is used to detect the resulting surface displacement. The complex displacement field is mapped as a function of source-to-receiver distance in order to extract the wavelength of the surface acoustic wave at a given excitation frequency, and the phase velocity is determined. The coatings tested exhibited spatial variations in thickness and mechanical properties. The measured surface wave dispersion curves were used to extract an effective value for the elastic modulus and the coating thickness. Nanoindentation was used to validate the measurements of the effective elastic modulus. The average elastic modulus measured through the coating thickness using nanoindentation is compared to the effective modulus found using the photoacoustic system. Optical microscopy is used to validate the thickness measurements. The results indicate that the photoacoustic microscopy technique can be used to estimate the effective elastic properties in coatings exhibiting spatial inhomogeneities, potentially providing valuable feedback for the optimization of the CVD growth process.

고출력 AlGaAs SCH-SQW 레이저 다이오드 개발 (Development of High-Power AlGaAs SCH-SQW Laser Diode)

  • 손진승;계용찬;권오대
    • 전자공학회논문지A
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    • 제30A권10호
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    • pp.27-32
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    • 1993
  • Separate-confinement hetero-structure (SCH) broad area Laser Diodes (LD's) were fabricated from $Al_{0.07}$Ga$_{0.93}$/. As single-quantum-well (SQW) grown by metal organic chemical vapor deposition (MOCVD). Under pulsed operation, we obtained maximum output powers of about 0.8watt/facet and 1.83watt/facet from LD's with 60$\mu$m and 160$\mu$m channel width, respectively, without facet coatings. The differential quantum efficiency of the 60$\mu$m wide LD was about 21.7%/facet and its threshold current density was about 1k [A/cm$^{2}$]. The differential quantum efficiency of the 160$\mu$m wide LD was about 25.6%/facet and its threshold current density was about 1k[A/cm$^{2}$]. The minimum threshold current density of 60$\mu$m wide LD's was 620[A/cm$^{2}$] when the cavity length was 603$\mu$m and the minimum threshold current density of 160$\mu$m wide Ld's was 675[A/cm$^{2}$] when the cavity length was 752$\mu$m. The internal quantum efficienty and the internal loss of both LD's were 92.3% and 18.1cm$^{1}$, respectively.

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PECVD 방법으로 제조된 비정질 Si 박막의 RTP를 이용한 결정화 연구 (Use of a Rapid Thermal Process Technique to study on the crystallization of amorphous Si films fabricated by PECVD)

  • 심찬호;김하나;김성준;김정우;권정열;이헌용
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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    • pp.2052-2054
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    • 2005
  • TFT-LCD requires to use poly silicon for High resolution and High integration. Thin film make of Poly silicon on the excimer laser-induced crystallization of PECVD(plasma-enhanced chemical vapor deposition)-grown amorphous silicon. In the thin film hydrogen affects to a device performance from bad elements like eruption, void and etc. So dehydrogenation prior to laser exposure was necessary. In this study, use RTP(Rapid Thermal Process) at various temperature from $670^{\circ}C$ to $750^{\circ}C$ and fabricate poly-silicon. it propose optimized RTP window to compare grain size to use poly silicon's SEM pictures and crystallization to analyze Raman curved lines.

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2파장 펌프-프로브 기법을 이용한 질화규소 박막의 열물성 평가 (Thermal Property Evaluation of a Silicon Nitride Thin-Film Using the Dual-Wavelength Pump-Probe Technique)

  • 김윤영
    • 한국재료학회지
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    • 제29권9호
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    • pp.547-552
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    • 2019
  • In the present study, the thermal conductivity of a silicon nitride($Si_3N_4$) thin-film is evaluated using the dual-wavelength pump-probe technique. A 100-nm thick $Si_3N_4$ film is deposited on a silicon (100) wafer using the radio frequency plasma enhanced chemical vapor deposition technique and film structural characteristics are observed using the X-ray reflectivity technique. The film's thermal conductivity is measured using a pump-probe setup powered by a femtosecond laser system of which pump-beam wavelength is frequency-doubled using a beta barium borate crystal. A multilayer transient heat conduction equation is numerically solved to quantify the film property. A finite difference method based on the Crank-Nicolson scheme is employed for the computation so that the experimental data can be curve-fitted. Results show that the thermal conductivity value of the film is lower than that of its bulk status by an order of magnitude. This investigation offers an effective way to evaluate thermophysical properties of nanoscale ceramic and dielectric materials with high temporal and spatial resolutions.

Measurement of the Thermal Conductivity of a Polycrystalline Diamond Thin Film via Light Source Thermal Analysis

  • Kim, Hojun;Kim, Daeyoon;Lee, Nagyeong;Lee, Yurim;Kim, Kwangbae;Song, Ohsung
    • 한국재료학회지
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    • 제31권12호
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    • pp.665-671
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    • 2021
  • A 1.8 ㎛ thick polycrystalline diamond (PCD) thin film layer is prepared on a Si(100) substrate using hot-filament chemical vapor deposition. Thereafter, its thermal conductivity is measured using the conventional laser flash analysis (LFA) method, a LaserPIT-M2 instrument, and the newly proposed light source thermal analysis (LSTA) method. The LSTA method measures the thermal conductivity of the prepared PCD thin film layer using an ultraviolet (UV) lamp with a wavelength of 395 nm as the heat source and a thermocouple installed at a specific distance. In addition, the microstructure and quality of the prepared PCD thin films are evaluated using an optical microscope, a field emission scanning electron microscope, and a micro-Raman spectroscope. The LFA, LaserPIT-M2, and LSTA determine the thermal conductivities of the PCD thin films, which are 1.7, 1430, and 213.43 W/(m·K), respectively, indicating that the LFA method and LaserPIT-M2 are prone to errors. Considering the grain size of PCD, we conclude that the LSTA method is the most reliable one for determining the thermal conductivity of the fabricated PCD thin film layers. Therefore, the proposed LSTA method presents significant potential for the accurate and reliable measurement of the thermal conductivity of PCD thin films.

IBC형 태양전지를 위한 균일하게 증착된 비정질 실리콘 층의 광섬유 레이저를 이용한 붕소 도핑 방법 (Boron Doping Method Using Fiber Laser Annealing of Uniformly Deposited Amorphous Silicon Layer for IBC Solar Cells)

  • 김성철;윤기찬;경도현;이영석;권태영;정우원;이준신
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2009년도 하계학술대회 논문집
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    • pp.456-456
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    • 2009
  • Boron doping on an n-type Si wafer is requisite process for IBC (Interdigitated Back Contact) solar cells. Fiber laser annealing is one of boron doping methods. For the boron doping, uniformly coated or deposited film is highly required. Plasma enhanced chemical vapor deposition (PECVD) method provides a uniform dopant film or layer which can facilitate doping. Because amorphous silicon layer absorption range for the wavelength of fiber laser does not match well for the direct annealing. In this study, to enhance thermal affection on the existing p-a-Si:H layer, a ${\mu}c$-Si:H intrinsic layer was deposited on the p-a-Si:H layer additionally by PECVD. To improve heat transfer rate to the amorphous silicon layer, and as heating both sides and protecting boron eliminating from the amorphous silicon layer. For p-a-Si:H layer with the ratio of $SiH_4$ : $B_2H_6$ : $H_2$ = 30 : 30 : 120, at $200^{\circ}C$, 50 W, 0.2 Torr for 30 minutes, and for ${\mu}c$-Si:H intrinsic layer, $SiH_4$ : $H_2$ = 10 : 300, at $200^{\circ}C$, 30 W, 0.5 Torr for 60 minutes, 2 cm $\times$ 2 cm size wafers were used. In consequence of comparing the results of lifetime measurement and sheet resistance relation, the laser condition set of 20 ~ 27 % of power, 150 ~ 160 kHz, 20 ~ 50 mm/s of marking speed, and $10\;{\sim}\;50 {\mu}m$ spacing with continuous wave mode of scanner lens showed the correlation between lifetime and sheet resistance as $100\;{\Omega}/sq$ and $11.8\;{\mu}s$ vs. $17\;{\Omega}/sq$ and $8.2\;{\mu}s$. Comparing to the singly deposited p-a-Si:H layer case, the additional ${\mu}c$-Si:H layer for doping resulted in no trade-offs, but showed slight improvement of both lifetime and sheet resistance, however sheet resistance might be confined by the additional intrinsic layer. This might come from the ineffective crystallization of amorphous silicon layer. For the additional layer case, lifetime and sheet resistance were measured as $84.8\;{\Omega}/sq$ and $11.09\;{\mu}s$ vs. $79.8\;{\Omega}/sq$ and $11.93\;{\mu}s$. The co-existence of $n^+$layeronthesamesurfaceandeliminating the laser damage should be taken into account for an IBC solar cell structure. Heavily doped uniform boron layer by fiber laser brings not only basic and essential conditions for the beginning step of IBC solar cell fabrication processes, but also the controllable doping concentration and depth that can be established according to the deposition conditions of layers.

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Stimulated Emission with 349-nm Wavelength in GaN/AlGaN MQWs by Optical Pumping

  • Kim, Sung-Bock;Bae, Sung-Bum;Ko, Young-Ho;Kim, Dong Churl;Nam, Eun-Soo
    • Applied Science and Convergence Technology
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    • 제26권4호
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    • pp.79-85
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    • 2017
  • The crack-free AlGaN template has been successfully grown by using selective area growth with triangular GaN facet. The triangular GaN stripe structure was obtained by vertical growth rate enhanced mode with low growth temperature of $950^{\circ}C$ and high growth pressure of 500 torr. The lateral growth rate enhanced mode of AlGaN for crack-free and flat surface was also investigated. Low pressure of 30 torr and high V/III ratio of 4400 were favorable for lateral growth of AlGaN. It was confirmed that the $4{\mu}m$ -thick $Al_{0.2}Ga_{0.8}N$ was crack-free over entire 2-inch wafer. The dislocation density of $Al_{0.2}Ga_{0.8}N$ was as low as ${\sim}7.6{\times}10^8/cm^2$ measured by cathodoluminescence. Based on the high quality AlGaN with low dislocation density, the ultraviolet laser diode epitaxy with cladding, waveguide and GaN/AlGaN multiple quantum well (MQW) was grown by metalorganic chemical vapor deposition. The stimulated emission at 349 nm with full width at half maximum of 1.8 nm from the MQW was observed through optical pumping experiment with 193 nm KrF laser. We also have fabricated the deep ridge type ultraviolet laser diode (UV-LD) with $5{\mu}m-wide$ and $700{\mu}m-long$ cavity for electrical properties. The turn on voltage was below 5 V and the resistance was ${\sim}55{\Omega}$ at applied voltage of 10 V. The amplified spontaneous emission spectrum of UV-LD was also observed from pulsed current injection.

PSG 광도파박막을 이용한 $1.3/1.55\mum$ WDM coupler의 설계 및 제작 (Design and fabrication of the $1.3/1.55\mum$ WDM coupler with the PSG waveguide films)

  • 전영윤;김한수;이용태;이형종
    • 한국광학회지
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    • 제6권4호
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    • pp.310-316
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    • 1995
  • 유한영역에서의 조화함수전개법으로 인접한 두 도파로 코어 중심간의 거리 및 도파로 변수에 따른 결합길이를 계산하여 $1.3/1.55\mum$ WDM coupler을 설계하였다. 저압화학기상증착법에 의해 PSG 도파박막을 제작하고 laser lithography와 $CF_4/O_2$ RIE 공정 등을 이용하여 WDM coupler를 제작하였다. 또한 광섬유를 지지 및 고정하기 위하여 Si 기판 위에 V-groove를 만들었으며 제작된 WDM coupler와 V-groove로 지지된 광섬유를 UV curing epoxy를 사용하여 접속하였다. 제작된 WDM coupler의 $1.3.\mum$, $1.55\mum$에서의 분지별 도파모드를 관측하고 분할비를 측정한 결과 최대 분할비는 각각 9dB, 12dB였다.

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