• Carbon letters
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• 제9권1호
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• pp.17-22
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• 2008

A carbon nanotube (CNT) of diameter ~20 nm has been synthesized by spray pyrolysis of turpentine oil using Ni/Fe catalyst. Pellet of CNTs has been used as a target to produce semiconducting carbon thin film of band gap 1.4 eV. Presence of oxygen pressure in the pulse laser deposition (PLD) chamber helped to control the $sp^3/sp^2$ ratio to achieve the desired band gap. Results are discussed with the help of Raman spectra, SEM TEM micrographs and optical measurements suggest that semiconducting carbon thin film deposited by PLD technique has retained its nanotubes structure except that its diameter has increased from 20 nm to 150 nm.

• 한국전기전자재료학회논문지
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• 제24권2호
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• pp.108-111
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• 2011

The semiconducting material of ZnO in II-VI group was well known as its good application for photo electronics, chemical sensors and field effect transistors due to the remarkable optical properties with wide energy band gap and great ionic reactivities. Up to now the growth of a good quality of ZnO film has been issued for better performances. Even though there were many deposition methods for making ZnO films, pulse laser deposition methods have been preferred for high crystalline films. In this report, the ZnO film was also created by pulsed laser deposition technique which also showed high crystalinity. By controlling several factors when deposited, it was investigated that the optimal condition for ZnO film formation. Mainly, oxygen partial pressures and growth temperatures were changed when ZnO films were synthesized and followed the characterization by HRXRD and AFM.

• 한국레이저가공학회지
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• 제2권3호
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• pp.52-61
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• 1999

The laser induced forward transfer(LIFT) technique employs a pulsed laser to transfer parts of a thin metal film from an optically transparent target onto an arbitrary substrate in close proximity to the metal film on the target. In this work, a two-step method, the combination of LIFT process, in which a Au film deposited on the $Al_2$O$_3$ substrate by Nd:YAG laser and subsequent Au electroless metal plating on the by LIFT process generated Au seed, was presented. The influence of laser parameters, wavelength, laser power, film thickness and overlap ratio of pulse tracks, on the shapes of deposit and conductor line after electroless plating is experimentally studied. As a results, the threshold power densities for ablation, deposition and metallization were determined and comparison of threshold value between the wave length 1064nm and the second harmonic generated 532nm. In odor to determine a possible application in the electronic industry, a smallest conduct spot size, line width and isolated line space were generated.

• 한국결정성장학회지
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• 제23권4호
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• pp.167-172
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• 2013

266 nm 파장을 갖는 Nd : YAG 레이저를 이용한 펄스레이저증착법(PLD)에 의해 모재인 $Al_2O_3$ 입자표면에 코팅된 $TiO_2$ 나노 입자를 제조하였다. 펄스레이저 에너지는 100 mJ/pulse로 고정하였으며, 레이저가 $TiO_2$ 타겟에 조사되는 동안 아르곤 가스를 챔버 내로 공급하였다. 이때, 압력은 $1{\times}10^{-2}Pa$에서 100 Pa로 변화시겼다. 증착된 나노 입자의 형태와 특성에 대한 증착 압력의 효과는 투과전자현미경과 에너지 분산형 X선 분광기를 이용하여 조사하였다. 모재 표면($Al_2O_3$)에 흡착된 나노 입자는 거의 구형이며 10~30 nm의 크기를 갖는다. 증착된 나노 입자의 형태는 기체 압력에 큰 영향을 받지 않는다. 그러나, 증착된 나노입자의 크기와 결정성은 기체 분압이 증가함에 따라서 증가한다. 이 방법에 의해서, 증착된 나노입자의 크기와 결정성은 기체 압력에 의해서 쉽게 조정할 수 있다.

• Journal of the Optical Society of Korea
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• 제18권1호
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• pp.50-54
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• 2014

In this paper we studied the laser-induced crater depth, mass, and emission spectra of laser-ablated high-density polyethylene (HDPE) polymer using the laser-induced plasma spectroscopy (LIPS) technique. This study was performed using a Nd:YAG laser with 100 mJ energy and 7 ns pulse width, focused normal to the surface of the sample. The nanoscale change in ablated depth versus number of laser pulses was studied. By using scanning electron microscope (SEM) images, the crater depth and ablated mass were estimated. The LIPS spectral intensities were observed for major and minor elements with depth. The comparison between the LIPS results and SEM images showed that LIPS could be used to estimate the crater depth, which is of interest for some applications such as thin-film lithography measurements and online measurements of thickness in film deposition techniques.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1858-1860
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• 1999

To fabricate superconducting multiplexers with narrow pass band characteristics and reduce the physical size of device, we have designed multiplexer using hair-pin type filters with the center frequency of 13.6 GHz. Multiplexers have been fabricated superconductor(HTS), because It has low surface resistance. The $YBa_2Cu_3O_{7-{\delta}}$(YBCO) films were deposited on MgO substrates$(20{\times}20{\times}0.5mm^3)$ by using pulsed laser deposition and conventional photo-lithographic methods were used to pattern the multiplexer. Epitaxial YBCO films were grown on(100) MgO substrates and showed strongly c_axis orientations observed by X-ray diffraction technique. Superconducting transition temperatures were measured to be about 89K. Simulated results of superconducting multiplexer consisting of hair-pin type filters show the insertion loss of about 1.2dB. The measured frequency response will be compared with the simulated results.

• Transactions on Electrical and Electronic Materials
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• 제16권6호
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• pp.334-337
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• 2015

Pure ZnO, ZnO nanowires doped with 3 wt.% Ga (3GZO) and doped with 3 wt.% Ag (3SZO) were grown by a hot-walled pulse laser deposition (HW-PLD) technique. The optical and chemical properties of Ga and Ag doped nanowires was analyzed. Nanowires were determined to be under 200 nm in diameter and several μm in length. Change of significant resistance was observed and the gas detection sensitivities of ZnO, 3GZO and 3SZO nanawires were compared. The sensitivities of ZnO, 3GZO, and 3SZO nanowire sensors were measured at 300℃ for 1 ppm of ethanol gas at 97%, 48%, and 203%, respectively.

• Journal of Magnetics
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• 제5권4호
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• pp.124-129
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• 2000

$Sm_2Fe_{17}N_x$ film magnets were prepared using a $Sm_2Fe_{17}$ target in a $N_2$ gas atmosphere using a Nd-YAG pulsed laser ablation technique. The effect of nitrogen pressure, deposition temperature, pulse time and film thickness on the structure and magnetic properties of $Sm_2Fe_{17}N_x$ film were studied. Increasing the nitrogen pressure up to 5 atm led to the formation of complete $Sm_2Fe_{17}N_x$ compound. Optimized magnetic properties with the nitrogenation temperature in the range 500-53$0^{\circ}C$ could be obtained by extending the nitrogenation time up to 4 hours. Relatively low coercivities of 400~600 Oe were found in $Sm_2Fe_{17}N_x$films 50~100 m thick, while a $4\piM_s$ of 10$\sim$12 kG could be achieved. In-plane anisotropy, which was the basic goal in this study, was achieved by controlling the nitrogenation parameters.

• 대한기계학회논문집B
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• 제27권2호
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• pp.188-196
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• 2003

Liquid-assisted cleaning technology utilizing a nanosecond laser pulse is effective for removing submicron particulates from a variety of solid substrates. In the technique, saturated vapor is condensed on a solid surface to form a thin liquid film and the film is evaporated explosively by laser heating. The present work studies the role of liquid-film evaporation in the cleaning process. First, optical interferometry is employed for in-situ monitoring the displacement of the laser-irradiated sample in the cleaning process. The experiments are performed for estimating the recoil force exerted on the target with and without liquid deposition. Secondly, time-resolved visualization and optical reflectance probing are also conducted for monitoring the phase-change kinetics and plume dynamics in vaporization of thin liquid layers. Discussions are made on the effect of liquid-film thickness and dynamics of plume and acoustic wave. The results confirm that cleaning force is generated when the bubble nuclei initially grow in the strongly superheated liquid.

• Transactions on Electrical and Electronic Materials
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• 제15권5호
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• pp.262-264
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• 2014

Pristine ZnO, 3 wt.% Ga-doped (3GZO) and 3 wt.% Ag-doped (3SZO) ZnO nanowires (NWs) were grown using the hot-walled pulse laser deposition (HW-PLD) technique. The doping of Ga and Ag in ZnO NWs was observed by analyzing the optical and chemical properties. We optimized the synthesis conditions, including processing temperature, time, gas flow, and distance between target and substrate for the growth of pristine and doped ZnO NWs. The diameter and length of pristine and doped ZnO NWs were controlled under 200 nm and several ${\mu}m$, respectively. Low temperature photoluminescence (PL) was performed to observe the optical property of doped NWs. We clearly observed the shift of the near band edge (NBE) emission by using low temperature PL. In the case of 3GZO and 3SZO NWs, the center photon energy of the NBE emissions shifted to low energy direction using the Burstein Moss effect. A strong donor-bound exciton peak was found in 3 GZO NWs, while an acceptor-bound exciton peak was found in 3SZO NWs. X-ray photoelectron spectroscopy (XPS) also indicated that the shift of binding energy was mainly attributed to the interaction between the metal ion and ZnO NWs.