Sm1Ba2Cu3O7−δSm_1Ba_2Cu_3O_{7-δ} 고온초전도박막 제작과 특성에 관한 연구

학위논문(박사)- 한국과학기술원 : 물리학과, 2004.2, [ v, 63 p. ]The growth properties and field dependent critical current densities of $Sm_{1+x}Ba{2-x}Cu_3O{7-\delta}$(SBCO) films on biaxially textured Ni tapes with $CeO_2/YSZ/CeO_2$ buffer layers were investigated.The window of substrate temperature($T_s$) for c-axis normal growth in 5mTorr of oxygen pressure were wider than $150^\circ C$. The upper limit of $T_s$-window was much higher than that of $Y_1Ba_2Cu_3O_{7-\delta}$(YBCO) films. Around the low limit of $T_s$, SBCO films grew in [103] normal textures. The zero field critical currents ($J_c$) were slightly smaller than those of YBCO films, while in high field regions critical current densities are much higher and the estimated pinning energies were less dependent on external fields than that of YBCO. We observed that a $Sm_1Ba_2Cu_3O_{7-\delta}(SBCO) film grown on a YSZ substrate with arbitrarily oriented crystal was textured in a single crystalline orientation, while there seems to be no noticeable relation between the crystalline orientations of the film and the substrate. The SBCO[103] axis was close to the surface normal axis. On the other hand, we could not grow an YBCO film on the same substrate, which implies the growth of SBCO film is more stable than YBCO film on that substrate. The qualities of SBCO films grown at substrate temperatures across a wide range of$680^\circ C$~$750^\circ C$were similar. The critical current density of this SBCO film was smaller than that of SBCO film on a RABiTS-Ni tape, which is several times smaller than that of the YBCO film of coated conductor. The transport properties of$Sm_1BA_2Cu_3O_{7-\delta}$films, which were grown on the bi-crystalline$SrTiO_3$substrates of$24^\circ$,$30^\circ$,$36.8^\circ$and$45^\circ$ misorientation angles, were investigated by the measurements of the Ⅰ-Ⅴ curves at 77K under various magnetic fields. When the voltages were high enough, the Ⅰ-Ⅴ curves became straight. The resistances estimated from the slopes were almost independ...한국과학기술원 : 물리학과

Fabrication and characterization of cylindrically textured high Tosuperconducting films

학위논문(석사) - 한국과학기술원 : 물리학과, 1998, [ ii, 50 p. ]한국과학기술원 : 물리학과

Apparatus for fabricating thin film

반응성 스퍼터링 증착의 경우 반응기체가 플라즈마화 되어 반응의 안정성에 나쁜 영향을 주게된다. 또한 반응기체가 스퍼터링 타겟 표면과 반응하여 스퍼터링 속도 및 박막 조성의 균일성이 떨어지게 된다. 그러나, 본 발명에 따른 박막제조장치에 의하면, 반응기체가 존재하는 반응공간과 스퍼터링 증착이 일어나는 스퍼터링 공간을 서로 분리하고 그 사이에 반응기체 및 스퍼터링용 기체를 배출하기 위한 펌핑 공간을 마련함으로써 두 기체의 혼합이 방지된 상태에서 박막을 제조할 수 있게된다. 그리고, 기판이 반응공간과 스퍼터링 공간을 번갈아 왕복할 수 있도록 되어 있기 때문에 증착공정과 반응공정이 연속적으로 이루어질 수 있게 된다. 따라서, 양질의 화합물 박막을 얻을 수 있게 된다. 스퍼터링, 반응성 스퍼터링, 플라즈마, 화합물 박