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EACVD로 Si 위에 성장한 다이아몬드 박막의 계면 접합강도
이철로(C. R. Lee),박재홍(J. H. Park),임재영(J. Y. Leem),김관식(K. S. Kim),천병선(B. S. Chun) 한국진공학회(ASCT) 1993 Applied Science and Convergence Technology Vol.2 No.3
필라멘트와 Si 기판 사이의 기전력을 20, 80, 140, 200V로 증가시키면서 EACVD에 의하여 성장된 다이아몬드 박막에 대하여 다이아몬드/Si 계면분석 및 계면강도를 측정하였다. 주사형전자현미경(SEM), 고분해능투과형전자현미경(HRTEM), 오제이전자분석기(AES)에 의해 계면상태를 분석한 결과, 기전력 증가에 따라 활성탄화수소 이온(C_mH_n^-) 에너지가 증가되어져 C_mH_n^-이 Si내로 침투(Impringement)가 증가되고 침투된 높은 에너지의 C_mH_n^-이 Si과 화학결합하여 생성되는 SiC층 깊이 및 농도 분포도 증가된다. 풀 시험(Pull test)에 의한 계면강도 측정 결과, SiC층 깊이 및 농도분포가 증가할수록 계면강도가 증가하였다. 관찰된 파면과 파면의 X-선 메핑 결과 및 HRTEM과 AES에 의한 분석 결과, 기전력 증가에 따라 공극율이 적고 치밀한 다이아몬드 박막이 성장된다. 그리고 생성되는 SiC층 농도 및 깊이 분포가 증가함에 따라 다이아몬드/Si 계면이 강화되고, 상대적으로 파괴는 다이아몬드/Si 계면이 아닌 SiC층이나 Si 내부에서 발생된다. 결국, 기전력을 증가하여 활성탄화수소 이온의 에너지를 증가함으로써 계면강도가 우수하며 공극율이 매우 적고 치밀한 다이아몬드 박막을 성장할 수 있다. The diamond thin films on Si which 20 V (Film A), 80 V (Film B), 140 V (Film C) and 200 V (Film D) had been applied respectively between filament and Si substrates during growth were analysed with SEM, HRTEM and AES. Judging from those results, the diffusion of carbon increased due to the increment of the energy of active hydrocarbon ion (C_mH_n^-) and also the SiC layers were formed as the result of chemical bonding of C_mH_n^- with Si. The amount and depth of SiC layer increased as the potentials increased. The interface adhesion of these films were also measured with Pull test which is the most accurate and general method in evaluation of thin film adhesion. The film (D) which SiC was formed most deeply and widely exhibited the most adhesion in diamond/Si interface. Meanwhiles, the film (A) which had most shallow SiC layer and low SiC concentration exhibited very weak adhesion compare to film (D). Judging from the observation and X-Ray Mapping of fracture surface, the film (D) was fractured in Si below interface and the film (A) was fractured in diamond thin film/Si interface. Also, there are many voids in film (A) and a little in film (D). Conclusively, it is possible to grow the high strength and condensed diamond thin film without pores because the energy of active hydrocarbon ion was increased by elevation of potentials during growth.
Diamond 박막 성장에 미치는 Si 표면 영향의 AES에 의한 연구
이철로(C. R. Lee),신용현(Y. H. Shin),임재영(J. Y. Leem),정광화(K. H. Chung),천병선(B. S. Chun) 한국진공학회(ASCT) 1993 Applied Science and Convergence Technology Vol.2 No.2
Si 기판 표면상태 변화와 관련된 핵생성 자유에너지 증가에 따른 다이아몬드 박막성장 거동을 관찰하였다. 표면 연마조건 변화에 따른 3가지 기판(A-Si, B-Si, C-Si) 위에 동일한 성장조건으로 다이아몬드를 성장하였으며, 이때 형상인자와 관련된 자유에너지 관계는 ΔG_(A-Si)<ΔG_(B-Si)<ΔG_(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 가장 적은 C 박막은 흑연이 많이 함유된 구상의 다이아몬드이다. The effect of nucleation free energy related to Si surface states on diamond film growth behavior has been studied. At first, the three kinds of diamond thin films (A, B, C) were deposited on various Si substrates (A-Si, B-Si, C-Si) whose surfaces were polished with 1 ㎛ diamond paste, 6 ㎛ Al₂O₃ powder and 12 ㎛ Al₂O₃ powder respectively. And then, relative nucleation free energy calculated is ΔG_(A-Si)<ΔG_(B-Si)<ΔG_(c-Si) Although there are some difference in grain size, shape and nucleation site, the thin films on A-Si and B-Si were diamond including a small amount of DLC which was confirmed by AES, SEM, XRD and RHEED. Namely, the diamonds of films (B) were not nucleated in scratches but in dents and larger in grain size compare with the film (C) of which diamond were nucleated not only scratches but also dents. And, the sphere diamond which is not general shape was grown on C-Si. After all, the sphere was turned out to be the diamond including much graphite as a result of the AES in situ depth profiling. Consequently, the diamond shape and quality grown on Si were changed from the crystal which the (100) and (110) planes were predominent to the crystal in which (111) plane was predominent, and next to sphere shape diamond including much graphite according as the nucleation free energy increases.
Phase Transitions and Collective Chain Dynamics in a Model Biomembrane C10H21NH3Cl
이철의,C. H. Lee,D. K. Oh,K. W. Lee 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV
Proton nuclear magnetic resonance (NMR) was employed to investigate the nature of the phase transitions and collective chain dynamics in a model biomembrane C10H21NH3Cl undergoing an irreversible structural change. The phase transitions were manifest in the second moment and laboratory frame spin-lattice relaxation rate measurements, with a hysteresis upon heating and cooling. The dimensionality and its crossover were explicitly conrmed as well. In addition, the rotating frame spin-lattice relaxation measurements revealed a low-frequency critical collective chain dynamics in the kHz regime, which is associated with the interdigitated to noninterdigitated chain congurational phase transition.
이철원(C.W. Lee),고영건(Y.G. Ko),신동혁(D.H. Shin) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
A study is made to put forward the new method of continuous-shear drawing(CSD), and investigate deformation behavior and microstructure evolution of aluminum alloy with a comparison of equal-channel angular (ECA) drawing. In contrast to ECA drawing, the die for CSD deformation can impart an additional strain to the workpiece since the diameter of the exit channel is narrower than that of its entrance channel. Although no significant crack occurs in all conditions during deformation, the sample via CSD method showed better surface quality as compared to ECA drawing. This is mainly ascribed to the fact that the sample is significantly bent rather than sheard when deforming though ECA drawing.