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열처리 온도에 따른 Si / Co / GaAs계의 계면반응 및 상평형에 관한 연구
곽준섭(J. S. Kwak),김화년(H. N. Kim),백홍구(H. K. Baik),신동원(D. W. Shin),박찬경(C. G. Park),김창수(C. S. Kim),노삼규(S. K. Noh) 한국진공학회(ASCT) 1995 Applied Science and Convergence Technology Vol.4 No.1
(001)방향 GaAs기판과 Si/Co 박막의 계면반응 및 상평형에 관한 연구를 300~700℃ 열처리 구간에서 행하였다. 반응에 의한 상전이 과정은 glancing angle X-ray diffraction(GXRD), Auger electron spectroscopy(AES) 및 cross-sectional transmission electron microscopy(XTEM)을 이용하여 분석하였다. Si/Co/GaAs계의 계면반응에서 Co는 380℃에서 GaAs 기판 및 Si와 반응하여 Co₂GaAs과 Co₂Si상을 형성하였다. 420℃에서 열처리 후, Co층은 모두 소모되었으며 단면구조는 Si/CoSi/CoGa(CoAs)/Co₂GaAs/GaAs으로 전이되었다. 460℃까지 온도를 올려 계속적인 반응을 일으키면 CoGa와 CoAs이 분해되면서 CoSi가 성장하였고, 600℃에서는 Co₂GaAs마저 분해되고 CoSi상이 성장하여 GaAs와 계면을 형성하였다. CoSi와 GaAs사이의 계면은 700℃의 고온까지 안정하였으며 이러한 계면반응 결과는 계산에 의하여 구한 Si-Co-Ga-As 4원계 상태도로부터 이해될 수 있었다. Interfacial reactions of Si/Co films on(001) oriented GaAs substrate, in the temperature range 300~700℃ for 30 min, have been investigated using glancing angle X-ray Diffraction(GXRD), Auger electron spectroscopy(AES), and cross-sectional transmission electron microscopy(XTEM). Cobalt starts to react with GaAs and Si at 380℃ by formation of Co₂GaAs, and Co₂Si phases, respectively. At 420℃, the entire layer of Co is consumed, and the layer structure is observed with the sequence Si/CoSi/CoGa(CoAs)/Co₂GaAs/GaAs. In the subsequent reaction, CoSi grows at the expense of the decompositions of CoGa and CoAs at 460℃. In addition, ternary phase is also decomposed and only CoSi phase is remained upon GaAs surface at 600℃. The interface between CoSi and GaAs is stable up to 700℃. The results of interfacial reactions can be understood from the calculated Si-Co-Ga-As quaternary phase diagram.
유효 구동력 개념을 이용한 고상 비정질화 반응의 예측에 관한 연구
곽준섭(J. S. Kwak),지응준(E. J. Chi),최정동(J. D. Choi),박상욱(S. W. Park),소명기(M. K. So),이성만(S. M. Lee),백홍구(H. K. Baik) 한국진공학회(ASCT) 1993 Applied Science and Convergence Technology Vol.2 No.1
이원계 박막확산쌍에서 열처리 방법에 의한 고상 비정질화 반응의 경향성을 예측하기 위하여 유효 구동력 개념을 제시하였다. 고상 비정질화 반응은 두 원소의 물리적 혼합물과 비정질상간의 최대 자유에너지차로 주어지는 열역학적 구동력(ΔG_(max))과 확산원소의 원자반경에 대한 기지의 유효 침입형자리 반경의 비로 주어지는 구조적 요소(R_(m/d))가 충족될 때 일어나는 빠른 확산에 의하여 발생된다고 고찰하고, 유효 구동력 기준을 이용하여 금속/금속계 뿐만아니라 금속/실리콘 계의 고상반응에 의한 비정질상 생성 경향성을 예측하고 실험결과들과 비교하여 잘 적용됨을 보였다. 또한, 유효 구동력 기준이 금속/실리콘 계에서 비정질상의 임계 성장두께 경향성의 예측에도 잘 적용됨을 보였다. It is proposed that formation and growth of amorphous interlayer through solid state amorphizing reaction can be predicted by the concept of effective driving force. The effective driving force consists of two factors; i) the thermodynamic driving force given by maximum free energy difference between physical mixture of binary elements and amorphous interlayer (ΔG_(max)) and ii) the structural factor given by a ratio between effective radius of interstitial site in host matrix and atomic radius of diffusing species (R_(m/d)). It is shown that the the criterion of effective driving force is successfully applied in the prediction of the formation of amorphous interlayer in metal/silicon systems as well as that of metal/metal systems from the comparison of experimental data. In addition, the concept of effective driving force can be well applied to predict the growth tendency of amorphous interlayer in metal/silicon systems.
75wt.%Ag-25wt.%Pd합금의 Zr첨가에 따른 미세조직변화와 기계적성질에 관한 연구
백홍구,김혜성,김명호,정호년,김경남 大韓齒科器材學會 1995 대한치과재료학회지 Vol.22 No.2
The effects of Zr addition on the microstructures and mechanical properties of 75wt.%Ag-25wt.%Pd alloy was studied. Grain size of the alloy was diminished with increasing amount of Zr addition, and it was notable when 0.2wt.% of Zr was added. when 0.6wt.% of Zr was added, coarse Pd₃Zr intermetallic compound(hexagonal, ??, ??) was precipitated in the matrix, and fine Pd₂Zr intermetallic compound(body centered tetragonal, ??, ??) could be seen by aging treatment at 450℃. Ultimate tensile strength of the alloy was increased with decreasing grain size until 0.2 wt.% Zr addition, but when an excess of Zr was added, ultimate tensile strength of the alloy was somewhat diminished despite of decreasing grain size. So, we concluded that the grain size of the 75wt.%Ag-25Wt.%Pd alloy was diminished by the Zr addition and mechanical properties were increased with decreasing grain size, and the optimum amount needed for hardening was 0.2 wt.%.
Ag-Pd-In 삼원계합금의 시효처리에 따른 기계적 성질변화와 미세상의 석출거동
백홍구,도정만,정호년,김명호,김경남 大韓齒科器材學會 1995 대한치과재료학회지 Vol.22 No.1
The effects of aging on the microstructures and mechanical properties of a 75wt.%Ag-25wt.%Pd alloy with various indium additions were studied. Tensile strength and hardness of the alloy increased with increasing aging temperature and time in the temperature range of 350 to 450℃. Similar trends were observed with increasing amount of In addition and precipitated InPd₃phase. Such features indicated that the alloy system considered in the study was age hardenable. In₂O₃oxide layers were observed to form at the outer surface of the specimen during heat treatment procedure. Based on the experimental observation, cracks were observed to form outer surface of the specimen followed by crack propagation along the grain boundary of the matrix, resulting in some decrease in the tensile strength.