• Journal of the Korean Vacuum Society
• /
• v.2 no.2
• /
• pp.255-260
• /
• 1993

UHV-LCVD system was constructed for high quality silicon nitride thin film fabrication. This system consisted of a reaction chamber, an introduction chamber with sample load lock entry, a carbinet for gas manipulation controlling gas flow, a $CO_2$ laser and a Fourier transform mass spectrometer. Although the UHV-LCVD system construction was more sophisticated than low pressure CVD, highly pure thin films were fabricated by controlling gas mixing ratio and flow rate in ultra high vacuum surroundings.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.9 no.3
• /
• pp.289-294
• /
• 1999

The charged clusters or particles, which contain hundreds to thousands of atoms or even more, are suggested to from in the gas phase in the thin film processes such as CVD, thermal evaporation, laser ablation, and flame deposition. All of these processes are also phase synthesis of the nanoparticels. Ion-induced or photo-induced nucleation is the main mechanism for the formation of these nanoclusters or nanoparticles in the gas phase. Charge clusters can make a dense film because of its self-organizing characteristics while neutral ones make a porous skeletal structure because of its Brownian coagulation. The charged cluster model can successfully explain the unusual phenomenon of simultaneous deposition and etching taking place in diamond and silicon CVD processes. It also provides a new interpretation on the selective deposition on a conducting material in the CVD process. The epitaxial sticking of the charged clusters on the growing surface is getting difficult as the cluster size increases, resulting in the nanostructure such as cauliflower or granular structures.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.103-103
• /
• 2003

ZnO$_{1-x}$(또는 Zn$_{1+x}$O) 산화아연은 과잉의 아연(또는 oxygen vacancy)이 도우너(donor) 역할을 하는 비화학양론적 n형 산화물 반도체이다. ZnO는 높은 투과율을 가지고 온도나 주변환경에 대해 매우 안정하며, 또한 이미 상용화된 ITO (Indium tin oxide)에 비해 식각 특성이 우수하고, 수소 플라즈마에 대한 저항성이 크다는 장점 때문에 가스센서와 디스플레이용 소자 등 다양한 분야에 응용이 가능하다. ZnO 박막은 CVD, Reactive Magnetron Sputtering, Electron-beam Evaporation 등 여러 가지방법으로 제작할 수 있다. 본 연구에서는 형성된 박막의 구성성분이 타겟의 성분과 유사하고 낯은 기판온도에서도 박막이 형성되어지는 장점을 가지는 Pulsed Laser Deposition 방법을 사용하여 유리 기판위에 ZnO 박막을 형성하였다.다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.656-660
• /
• 2003

We studied the crystallization behavior of LP-CVD a-Si film using UV pulsed laser. With increase in the shot number of irradiation by fixing its energy density, poly-Si film having a large grain size of $0.5 {\mu}m$ was obtained. By analyzing the crystallized Si films using optical analysis such as Raman spectroscopy or AFM technique etc., conspicuous correlation between the grain size and the resultant film properties such as the stress or the roughness has been found. With the increase in the energy density or the shots number of laser, remarkable grain growth occurred following to the roughness formation corresponding to the increase in the tensile stress.

• Proceedings of the KIEE Conference
• /
• 1990.07a
• /
• pp.180-182
• /
• 1990

Today, according to the temperature lowering of VLSI technology which have been required, the new thin film technology of low temperature have appeared. Plasma CVD method, one of low temperature technologies, have major problems with many interface trap defects. In this paper, we prepared ammonia free SiN film containing small H that acts as a defect impurity, and investigated the electrical properties of Laser assisted deposition film.

• Bulletin of the Korean Chemical Society
• /
• v.15 no.1
• /
• pp.28-33
• /
• 1994

The laser-assisted chemical vapor deposition (LCVD) is described, by which the growth of single-phase GaN epitaxy is achieved at lower temperatures. Trimethylgallium (TMG) and ammonia are used as source gases to deposit the epitaxial films of GaN under the irradiation of ArF excimer laser (193 nm). The as-grown deposits are obtained on c-face sapphire surface near 700$^{\circ}$C, which is substantially reduced, relative to the temperatures in conventional thermolytic processes. To overcome the lattice mismatch between c-face sapphire and GaN ad-layer, aluminum nitride(AlN) is predeposited as buffer layer prior to the deposition of GaN. The gas phase interaction is monitored by means of quadrupole mass analyzer (QMA). The stoichiometric deposition is ascertained by X-ray photoelectron spectroscopy (XPS). The GaN deposits thus obtained are characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and van der Pauw method.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.179-179
• /
• 2010

1차원 나노구조를 갖는 ZnO를 성장하기 위해 Laser ablation, Chemical vapor deposition (CVD), Chemical transport method, Molecular beam epitaxy, Sputtering 등의 다양한 형성법들이 이용되어지고 있다. 특히 대량생산과 경제성 측면에서 많은 장점을 가지고 있는 CVD를 이용한 ZnO 성장 및 응용 연구가 활발하게 수행되고 있다. 본 연구에서는 Thermal CVD를 이용하여 반응물질과 기판 사이의 거리, 기판온도, $O_2$/Zn 비율 등의 성장변수를 변화시켜 ZnO 나노구조를 성장하고 구조 및 광학적 특성을 연구하였다. Scanning electron microscope를 통한 구조 특성평가 결과 반응물질과 기판 사이의 거리가 13 cm 이하의 조건에서 ZnO 나노구조들은 나노판(Nanosheet)과 나노선(Nanowire)이 혼재하여 성장된 것을 보였다. 그리고 반응물질과 기판사이의 거리가 15 cm 이상부터 나노판이 없어지고 수직한 ZnO 나노막대(Nanorod)가 형성되었다. 상온 Photoluminescence 스펙트럼에서 반응물질과 기판사이의 거리가 5에서 15 cm로 증가할수록 결함 (Defect)에 의해 발생된 515 nm 파장의 최대세기 (Maximum intensity)가 10배 이상 감소한 반면, ZnO 나노구조에 의한 378 nm 파장의 NBE발광 (Near band edge emission)은 8배 이상 증가하였다. 이러한 구조 및 광학적 결과로부터, 질서 없이 성장된 것보다 수직 성장된 ZnO 나노구조의 결정질(Crystal quality)이 좋은 것을 확인하였다. 이를 바탕으로 성장변수에 따른 ZnO 나노구조의 형성 메커니즘을 Zn와 O 원자의 성장거동을 기반으로 한 모델을 이용하여 해석하였다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.290.1-290.1
• /
• 2016

Grapehen, a single atomic layer of graphite, has been in the spotlight and researched in vaious fields, because its fine mechanical, electrical properties, flexibility and transparence. Synthesis methods for large-area graphene such as chemical vaper deposition (CVD) and mechanical, chemical exfoliation have been reported. In particular, chemical exfoliation method receive attention due to low cost process. Chemical exfoliation method require reduction of graphene oxide in the process of exfoliation such as chemical reduction by strong reductant, thermal reduction on high temperature, and optical reduction via ultraviolet light exposure. Among these reduction methods, optical reduction is free from damage by strong reductant and high temperature. However, optical reduction is economically infeasible because the high cost of short-wavelength ultraviolet light sorce. In this paper, we make graphene-oxide and lanthanoid ion mixture aqueous solution which has highly optical absorbency in selective wevelength region. Sequentially, we synthesize reduced graphene oxide (RGO) using the solution and visible laser beam. Concretely, graphene oxide is made by modified hummer's method and mix with 1 ml each ultraviolet ray absorbent Gd3+ ion, Green laser absorbent Tb3+ ion, Red laser absorbent Eu3+ ion. After that, we revivify graphene oxide by laser exposure of 300 ~ 800 nm layser 1mW/cm2 +. We demonstrate reproducibility and repeatability of RGO through FT-IR, UV-VIS, Low temperature PL, SEM, XPS and electrical measurement.

• Proceedings of the Optical Society of Korea Conference
• /
• 1989.02a
• /
• pp.210-213
• /
• 1989

An early phase of the OMVPE and LACVD studies of growing AlGaAs/GaAs films is reported. The AlGaAs/GaAs epitaxy to the level of obtaining MOW structures is a crucial step for the fabrication of the devices such as SEED and/or DOES which are basic parts of the OEIC. The analysis of the OMVPE system is shown for this purpose and the basic results of the LACVD are also presented.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.23 no.5
• /
• pp.235-240
• /
• 2013

Pure-carbon materials such as graphite, graphene, carbon nanotubes, and diamond have very high thermal conductivities. The reported thermal conductivity of graphene is in the range 3000~5000W/m-K at room temperature. Here, we developed graphene/cu foam hybrid type heat spreader to obtain higher thermal conductivity than Cu foam. Hybrid materials were characterized using optical microscopy (OM), scanning electron microscopy (SEM) and thermal conductivity measurement system; LFA (Laser Flash Analysis @ LFA 447, NETZSCH). We suggest that excellent thermal properties of graphene/cu foam hybrid structures are beneficial for all proposed electrical applications and can lead to a thermal management application.