• 한국진공학회지
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• 제2권2호
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• pp.199-208
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• 1993

Si 기판 표면상태 변화와 관련된 핵생성 자유에너지 증가에 따른 다이아몬드 박막성장 거동을 관찰하였다. 표면 염마조건 변화에 따른 3가지 기판(A-Si, B-Si, C-Si)위에 동일한 성장조건으로 다이아몬드를 성장하였으며, 이때 형상인자와 관련된 자유에너지 관계는 ${\Delta}G_{A-Si}<{\Delta}G_{B-Si}<{\Delta}G_{C-Si}$이다. AES, SEM, XRD, RHEED에 의해 각각의 박막 A, B, C를 조사한 결과, 핵생성 자유에너지가 가장 적은 A 박막은 (100) (110) 면이 지배적인 고품위 다이아몬드 박막이다. 자유에너지가 A에 비해 다소 적은 B 박막은 (111) 면이 지배적인 8면체 다이아몬드 박막이고, 자유에너지가 자장 적은 C 박막은 흑연이 많이 함유된 구상의 다이아몬드이다.

• 한국세라믹학회지
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• 제28권10호
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• pp.777-784
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• 1991

Diamond films have been growth by the hot-filament chemical vapor deposition (HFCVD) using CH4 and H2 gaseous mixture on the Si substrate. The experimental results indicated that the deposits were pure diamond and contained no amount of non-diamond phases such as amorphous carbon or graphite. The diamond films were deposited well at the conditions: the filament temperature of 210$0^{\circ}C$, the substrate temperature of 77$0^{\circ}C$, the CH4 concentration of 1.76%, the reactor pressure of 30 torr, and the deposition time of 7 hr. At this growth condition, the maximum deposition rate was 2 ${\mu}{\textrm}{m}$/hr. X-ray diffraction patterns and texture coefficient results showed that preferred orientation of the diamond films was {111} orientation under all experimental conditions.

• 항공우주시스템공학회지
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• 제14권2호
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• pp.28-35
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• 2020

In this paper, we present a design for a retraction-type actuator (ReACT) that has the characteristics of both thermomechanical metamaterials and displacement amplification mechanisms. The ReACT consists of an actuating bar, a diamond-shaped displacement amplification (DA) structure, and a slot for loading thin-film heaters formed through the actuating bar. When power is supplied to the thin film heater, the actuating bars contacting the heater thermally expand, and the diamond-shaped DA structures retract in the longitudinal direction. The performance characteristics of the ReACT, such as temperature distribution and retracting displacement, were calculated with thermomechanical analysis methods using the finite element method (FEM). Subsequently, the ReACTs were fabricated using a polymer-based 3D printer that can easily execute complex structures, and the performance of the ReACT was evaluated through repeated tests under various temperature conditions. The results of the performance evaluation were compared with the results of the FEM analysis.

• The Korean Journal of Ceramics
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• 제3권3호
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• pp.173-176
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• 1997

Direct metal ion beam deposition is considered to be a whole new thin film deposition technique. Unlike other conventional thin film deposition processes, the individual deposition particles carry its own ion beam energies which are directly coupled for the formation of this films. Due to the nature of ion beams, the energies can be controlled precisely and eventually can be tuned for optimizing the process. SKION's negative C- ion beam source is used to investigate the initial nucleation mechanism and growth. Strong C- ion beam energy dependence has been observed. Complete phase control of sp3 and sp3, control of the C/SiC/Si interface layer, control of crystalline and amorphous mode growth, and optimization of the physical properties for corresponding applications can be achieved.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.290-290
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• 2011

In this study Diamond-like carbon (DLC) films were deposited on p-type Si substrates using a Radio-Frequency magnetron Sputtering system. The DLC film was deposited by bombarding graphite target with a N2/Ar plasma mixture with various conditions: substrate, pressure, deposition time, temperature of substrate, power and ratio of gas mixture. The effect on the conduction and hardness of DLC thin films were investigated. The conduction of DLC films were measured by I-V measurement. In addition, Raman analysis was performed to study the chemical bonding structure. The hardness was measured by Nano indentation. Atomic Force Microscopy was used for determined surface morphology of DLC film.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2002년도 정기총회 및 추계학술연구발표회
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• pp.20-20
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• 2002

Based on experimental and theoretical analyses, we suggested a new possibility that the CVD diamond films grow not by the atomic unit but by the charged clusters containing a few hundreds of carbon atoms, which form spontaneously in the gas phase [J. Crysta] Growth 62 (1996) 55]. These hypothetical negatively-charged clusters were experimentally confirmed under a typical hot-filament diamond CVD process. Thin film growth by charged clusters or gas phase colloids of a few nanometers was also confirmed in Si and ZrO₂ CVD and appears to be general in many other CVD processes. Many puzzling phenomena in the CVD process such as selective deposition and nanowire growth could be explained by the deposition behavior of charged clusters. Charged clusters were shown to generate and contribute at least partially to the film deposition by thermal evaporation. Origin of charging at the relatively low temperature was explained by the surface ionization described by Saha-Langmuir equation. The hot surface with a high work function favors positive charging of clusters while that of a low work function favors negative charging.

• Transactions on Electrical and Electronic Materials
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• 제7권6호
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• pp.297-300
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• 2006

The response surface modeling of the pretilt angle control using ion-beam (IB) alignment on nitrogen doped diamond-like carbon (NDLC) thin film layer is investigated. This modeling is used to analyze the variation of the pretilt angle under various process conditions. IB exposure angle and IB exposure time are considered as input factors. The analysis of variance technique is settled to analyze the statistical significance, and effect plots are also investigated to examine the relationships between the process parameters and the response. The model can allow us to reliably predict the pretilt angle with respect to the varying process conditions.

• 항공우주시스템공학회지
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• 제15권6호
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• pp.1-9
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• 2021

In this study, a new design of an extension-type actuator (ExACT) is proposed based on a chevron structure with displacement amplification mechanisms by local heating. ExACT comprises diamond-shaped displacement amplification structures (DASs) containing axially oriented V-shaped chevron beams, a support bar that restricts lateral heat deformation, and a loading slot for thin-film heaters. On heating the thin film heater, the diamond-shaped DASs undergo thermal expansion. However, lateral expansion is restricted by the support bar, leading to displacement amplification in the axial direction. The performance parameters of ExACT such as temperature distribution and extended displacement is calculated using thermo-mechanical analysis methods with the finite element method (FEM) tool. Subsequently, the ExACTs are fabricated using a polymer-based 3D printer capable of reproducing complex structures, and the performance of ExACTs is evaluated under various temperature conditions. Finally, the performance evaluation results were compared with those of the FEM analysis.

• 한국재료학회지
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• 제31권7호
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• pp.403-408
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• 2021

Various surface colors are predicted and implemented using the interference color generated by controlling the thickness of nano-level diamond like carbon (DLC) thin film. Samples having thicknesses of up to 385 nm and various interference colors are prepared using a single crystal silicon (100) substrate with changing processing times at low temperature by plasma-enhanced chemical vapor deposition. The thickness, surface roughness, color, phases, and anti-scratch performance under each condition are analyzed using a scanning electron microscope, colorimeter, micro-Raman device, and scratch tester. Coating with the same uniformity as the surface roughness of the substrate is possible over the entire experimental thickness range, and more than five different colors are implemented at this time. The color matched with the color predicted by the model, assuming only the reflection mode of the thin film. All the DLC thin films show constant D/G peak fraction without significant change, and have anti-scratch values of about 19 N. The results indicate the possibility that nano-level DLC thin films with various interference colors can be applied to exterior materials of actual mobile devices.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.107-107
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• 2003