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${La_{1-x}}{Sr_x}{MnO_{3-{\delta}}}$(0.19$\leq$x$\leq$0.31) 박막의 결정구조 및 전기전도 특성
허현,임세주,조남희,Heo, H.,Lim, S.J.,Cho, N-H. 한국재료학회 2000 한국재료학회지 Vol.10 No.6
기판온도, 박막조성 및 증착후 열처리 등의 조건에 따른 ${La_{1-x}}{Sr_x}{MnO_{3-{\delta}}}$(0.19$\leq$x$\leq$0.31) 박막의 결절구조와 전기전도 특성을 조사하였다. 스퍼터법을 이용하여 $500^{\circ}C$에서 증착된 박막은 강한 <001> 우선배향성과 유사정방정(pseudo-tetrag-onal, a/c-=0.97) 결정체를 나타냈다. 이러한 박막의 단위포는 산소분위기 내에서 증착후 열처리에 의하여 입장정 결정계로 변하였다. $La_{0.67}Sr_{0.33}MnO_3$ 조성의 주타겟과 $La_{0.3}Sr_{0.7}MnO_3$조성의 보조타겟을 동시에 이용하여 박막의 조성을 조절하였다. 보조타겟의 개수에 따라 박막내의 Sr 함량(x)은 0.19-0.31 범위의 값을 나타내었으며, x값이 0.19로부터 0.31로 증가시 금소-반도체의 전이 온도가 상승하였고, 전지비저항이 대체로 감소하였다. 0.18 T의 자기장 하에서, $La_{0.69}Sr_{0.31}MnO_3$조성의 박막의 자기저항변화 MR((%) = (${\rho}_o-{\rho}_H/{\rho}_H$)는 약 390% 이었다. We investigated the effect of substrate temperature, chemical composition and post-deposition heat-treatment on the crystal structure and electrical transport of $La_{1-x}Sr_xMnO_{3-{\delta}}$(0.19${\leq}x{\leq}$0.31) thin films. As-prepared $La_{1-x}Sr_xMnO_{3-{\delta}}$ films grown at $500^{\circ}C$ by sputter techniques were found to have the pseudo-tetragonal system(a/c=0.97) and a highly preferential <001> orientation. The films were changed to be of the cubic system by post-deposition annealing at around $900^{\circ}C$. A main target of $La_{0.67}Sr_{0.33}MnO_3$ as well as auxliary targets of $La_{0.3}Sr_{0.7}MnO_3$ ceramics were co-sputtered to control the chemical composition of the film. The Sr content(x) of the film ranged from 0.19 to 0.31, depending on the number of the auxiliary target. When x increased from 0.19 to 0.31, the electrical resistivity of the film decreased and the transition temperature between metal and semiconductor shifted to higher temperature. With a magnetic field of 0.18 T, the magneto-resistance ratio (MR(%) = (${\rho}_o-{\rho}_H/{\rho}_H$) of the $La_{0.69}Sr_{0.31}MnO_3$ thin film was about 390%.
고주파 마그네트론 스퍼터 기법으로 제조된 Ce : YIG 박막의 화학 조성, 미세구조 및 자기적 특성
박명범(M.-B. Park),조남희(N.-H. Cho) 한국자기학회 2000 韓國磁氣學會誌 Vol.10 No.3
Cerium substituted YIG thin films were grown by rf magnetron sputter techniques. We investigated the effects of post-deposition heat-treatment as well as various deposition parameters such as substrate materials, substrate temperature, sputter power, and sputter gas types on the crystallinity, chemical composition, microstructure and magnetic characteristics of the films. Post-deposition heat treatment over 750℃ was applied to crystallize as-prepared amorphous films, and a strong tendency of particular crystallographic planes lying parallel to substrate surface was observed for the post-deposition heat-treated films on GGG substrate. The chemical composition of the films exhibited a wide range of chemical stoichiometry depending on the oxygen fraction of sputter gas, and in particular the composition of the film deposited in sputter gas with an oxygen fraction of R=10% was Ce_(0.23)Y_(1.30)Fe_(3.50)O₁₂. With raising the temperature of post-deposition heat-treatment from 900℃ to 1100℃, the surface roughness of the film on GGG substrates increased from about 3 ㎚ to 40 ㎚, but their coercive force and ferromagnetic resonance line width decreased from 0.477 ㎄/m to 0.369 ㎄/m and from 12.5 ㎄/m to 8.36 ㎄/m, respectively.