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방사광 광전자 분광법을 이용한 Co - Pd 합금박막의 전자구조 연구
강정수(J. S. Kang),권세균(S. K. Kwon),하양장(Y. J. Ha),민병일(B. I. Min),조용필(Y. P. Cho),이창섭(C. S. Ri),정인범(I. B. Chung),구양모(Y. M. Koo),김건호(K. H. Kim),김봉수(B. S. Kim) 한국자기학회 1996 韓國磁氣學會誌 Vol.6 No.6
Valence band photoemission spectroscopy (PES) measurements have been performed for Co_xPd_(100-x) alloy films using synchrotron radiation (x=0, 25, 40, 65). Then the partial spectral weight distributions (PSW’s) of Co 3d and Pd 4d electrons have been determined. The Co 3d PSW’s exhibit some structures which are quite different from those of the Co film for x<25 %, whereas they become very similar to those of the Co film for x>40 %. For x<25 %, the peak near the Fermi level (E_F) and a shoulder around 2 eV binding energy in the Co 3d PSW reflect large hybridization between Pd 4d and Co 3d electrons, suggesting that the hybridization might play an inportant role in determining perpendicualr magnetic anisotropy. The Pd 4d PSW’s in Co-Pd alloy films are found to have larger FWHM’s (full widths at half maximum), larger binding energies of the main peaks, and larger spectral intensities at E_F than the PES spectrum of the Pd film. The FWHM of the Pd 4d PSW increases with decreasing Pd concentration, which are considered to reflect the disordering effect in the alloy formation or the change in the Pd 4d electronic structure due to hybridization between Co 3d and Pd 4d electrons.
Valence Band Photoemission Study of Co / Pd Multilayer
강정수(J.-S. Kang),강상국(S.K. Kim),정재인(J.I. Jeong),홍재화(J.H. Hong),이영백(Y.P. Lee),신현준(H.J. Shin),C. G. Olsong(C. G. Olsong) 한국자기학회 1993 韓國磁氣學會誌 Vol.3 No.1
We report the photoemission (PES) studies for the Co /Pd multilayer. The Co 3d PES spectrum of Co /Pd exhibits two interesting features, one near the Fermi energy, E_F, and another at ~2.5 eV below E_F. the Co 3d peak near E_F of Co /Pd is much narrower than that of the bulk Co, consistent with the enhanced Co magnetic moment in Co /Pd compared to that in the bulk Co. The Co 3d feature at ~ -2.5 eV resembles the Pd valence band structures, which suggests a substantial hybridization between the Co and Pd sublayers. The Co 3d PES spectrum of Co /Pd is compared with the existing band structures, obtained using the local spin density functional calculations. A reasonable agreement is found concerning the bandwidth of the occupied part of the Co 3d band, whereas a narrow Co 3d peak near E_F seems not to be described by the band structure calculations.
홍재화(J.H. Hong),강정수(J.S. Kang),정재인(J.I. Jeong),전인준(I.J. Jeon),이영백(Y.P. Lee) 한국진공학회(ASCT) 1992 Applied Science and Convergence Technology Vol.1 No.2
냉연강판의 성능은 그 표면 상태에 의해서 많은 영향을 받는다. Temper-color(T/C)층은 tempering 과정 중 형성되는 다양한 색깔의 얇은 산화층으로서, 우수한 표면 품질을 갖기 위해서는 방지 또는 제어되어져야 한다. T/C 현상을 이해하기 위하여 여러 가지 표면 분석방법이 동원되었다. 유백색 T/C층의 표면은 1 ㎛ 크기의 구형의 미세구조로 구성되어 있었다. 소둔과정 중 C, Si, Mn과 Al이 표면으로 농화됨을 알았고, Mn과 C은 정상시료에서 보다 T/C 시료에서 농화가 심하였다. T/C 시료에서의 산화층 두께는 정상시료의 60-100 Å 보다 매우 두꺼웠으나, 발생 정도에 따라 변화하였다. T/C층 내의 각 원소 산화 상태는, Si은 SiO₂의 상태로, Mn은 MnO나 MnO₂의 상태로 Fe는 극표면층의 Fe₂O₃ 상태를 제외하고는 metallic 상태로 분석되었다. The performance of the cold-rolled steel sheet is affected strongly by the surface conditions. Temper-colored (T/C) layer, which is the formation of a thin colored layer on the surface in the tempering process, is one of the phenomena which should be overcome to secure the improved surface quality. The layers were exposed to a variety of surface-analysis techniques for the characterization. The surface of milky-color T/C film consists of droplet-shaped microstructures in the size of around 1 ㎛. C, Si, Mn and Al are segregated to the surface during annealing. Mn and C are found to be more enriched at the surface of T/C sample than the normal one. The thickness of the oxide of T/C sample is much larger than the normal one of 60-100 Å, but varies in a wide range according to the degree of T/C. The oxidation state of Si in T/C film was analyzed to be SiO₂, and that of Mn to be MnO or MnO₂. On the contrary, Fe was metallic with Fe₂O₃ phase only at the extreme surface.
질화붕소가 스프레이코팅된 흑연과 용융 알미늄간의 진공에서의 반응기구
정재인(J. I. Jeong),임병문(B. M. Lim),문종호(J. H. Moon),홍재화(J. H. Hong),강정수(J. S. Kang),이영백(Y. P. Lee) 한국진공학회(ASCT) 1994 Applied Science and Convergence Technology Vol.3 No.1
질화붕소를 스프레이코팅한 흑연과 용융 알미늄간의 진공에서의 반응기구를 여러 가지 분석장치를 이용하여 조사하였다. 계면에 형성된 화합물층은 잘 정의된 형태를 보였으며, Al₄C₃와 Al_8B₄C_7의 혼합상이 흑연 바로 위에 형성되었고 그 위는 주로 AlN층으로 이루어져 있었다. 이러한 화합물의 생성과정과 반응기구를 자유에너지 관점에서 논의하였다. 이러한 방법으로 흑연 보우트를 제조하여 알미늄 증발에 이용하였을 경우, 매우 안정적인 증발 양상을 보였으며, 0.6 ㎛/min 이상의 매우 높은 증발율을 얻을 수 있음을 확인하였다. 또한 제조원가가 저렴하고 (TiB₂BN 보우트의 약 1/100), 전자빔 증발에 의해 형성된 피막과 비교하여 손색이 없는 피막을 얻을 수 있어 새로운 저항가열 증발원으로서의 이용 가능성을 확인하였다. We have investigated the reaction mechanism between BN-sprayed graphite and molten Al in vacuum using the various analytical tools. The interfacial compound layers were well-defined, and made mainly of AlN with underlying thin mixed layer of Al₄C₃ and Al_8B₄C_7. The analysis results were interpreted in terms of the free energy of formation. We prepared the BN-sprayed and annealed graphite boat, and evaluated the performance characteristics for the evaporation of Al. The evaporation was very stable, and also extended lifetime and enhanced rate up to 0.6 ㎛/min were obtained at a manufacturing cost of about 1% compared with current TiB₂ㆍBN boat.
방사광을 이용한 FeV<SUB>2</SUB>O<SUB>4</SUB> 스피넬 산화물의 덩치상태와 분말상태의 전자구조 차이 연구
황지훈(Jihoon Hwang),김대현(D. H. Kim),이은숙(Eunsook Lee),강정수(J.-S. Kang),김우철(W. C. Kim),김철성(C. S. Kim),한상욱(S. W. Han),홍순철(S. C. Hong),박병규(B.-G. Park),김재영(J.-Y. Kim) 한국자기학회 2011 韓國磁氣學會誌 Vol.21 No.6
The electronic structure of ferrimagnetic spinel oxide of FeV<SUB>2</SUB>O<SUB>4</SUB> has been investigated by employing soft x-ray absorption spectroscopy (XAS) and soft x-ray magnetic circular dichroism (XMCD). The Fe 2p and V 2p XAS spectra show that the valence states of Fe and V ions are ~Fe<sup>2.3+</sup> mixed-valent states and ~V3+ states, respectively. In Fe 2p XMCD spectra, finite XMCD signals are observed for divalent Fe<sup>2+</sup> states only, but not for Fe<sup>3+</sup> states. This finding indicates that the magnetic moments of Fe<sup>2+</sup> ions are ordered ferromagnetically but that those of Fe<SUP>3+</SUP> ions are cancelled, implying that Fe<sup>2+</sup> ions play an important role in determining magnetic properties of FeV<SUB>2</SUB>O<SUB>4</SUB>.
Adhesion Enhancement of Thin Film Metals on Polyimide Substrates by Bias Sputtering
김선영,조성수,강정수,김영호,Kim S. Y.,Jo S. S.,Kang J. S.,Kim Y. H. 한국마이크로전자및패키징학회 2005 마이크로전자 및 패키징학회지 Vol.12 No.3
Al, Ti, Ta 및 Cr 박막을 DC 마그네트론 스퍼터링방법으로 0 - 800 W의 RF 바이어스로 폴리이미드 기판에 가하면서 증착한 후 금속박막의 접착성을 연구하였다. 접착력은 $90^{\circ}$ 필 테스트로 평가하였다. 필 테스트 결과 모든 시편에서 기판에 RF 바이어스를 가하면 접착력이 향상되었다. RF바이어스를 가한 시편은 필링 도중 계면근처의 폴리이미드 내에서 파괴가 일어나면서 소성변형이 심하게 발생하였다. 단면 투과전자현미경 관찰에 의하면 금속/폴리이미드 계면은 분명하지 않고 복잡한 형상을 띄고 있었다. 이런 복잡한 계면은 RF 바이어스의 영향으로 생겼으며 접착력 향상의 주요 요인이었다. Al, Ti, Ta, and Cr thin films were deposited on a polyimide substrate using DC magnetron sputter to study the adhesion characteristics of metal films on polyimide substrates, while RF bias of 0 - 400 W was applied to the substrate during DC sputtering. The adhesion strength was evaluated using a 90-degree peel test. The peel tests showed that the adhesion strength was enhanced by applying the RF bias to the substrate in all specimens. Scanning electron microscopy and Auger depth profile of the fractured surfaces indicate that the polyimide underwent cohesive failure during peeling and heavy deformation was also observed in the metal films peeled from the polyimide substrate when the RF bias applied during the deposition. Cross-sectional transmission electron microscopy revealed that the metal/polyimide interface was not clear and complicated. This complicated interface, likely formed due to the RF bias applied to the substrate, was attributed to the adhesion enhancement observed during the bias sputtering.