Deposition of $MgB_2$ Thin Films on Alumina-Buffered Si Substrates by using Hybrid Physical-Chemical Vapor Deposition Method

혼성물리화학기상 증착법에 의한 알루미나 완충층을 가진 실리콘 기판 위의 $MgB_2$ 박막제조에 대한 연구

  • Lee, T.G. (BK21 Division and Department of Physics, Sungkyunkwan University) ;
  • Park, S.W. (BK21 Division and Department of Physics, Sungkyunkwan University) ;
  • Seong, W.K. (BK21 Division and Department of Physics, Sungkyunkwan University) ;
  • Huh, J.Y. (BK21 Division and Department of Physics, Sungkyunkwan University) ;
  • Jung, S.G. (BK21 Division and Department of Physics, Sungkyunkwan University) ;
  • Lee, B.K. (Device Materials Research Center, Korea Research Institute of Chemical Technology) ;
  • An, K.S. (Device Materials Research Center, Korea Research Institute of Chemical Technology) ;
  • Kang, W.N. (BK21 Division and Department of Physics, Sungkyunkwan University)
  • Published : 2008.04.30

Abstract

[ $MgB_2$ ] thin films were fabricated using hybrid physical-chemical vapor deposition (HPCVD) method on silicon substrates with buffers of alumina grown by using atomic layer deposition method. The growth war in a range of temperatures $500\;{\sim}\;600^{\circ}C$ and under the reactor pressures of $25\;{\sim}\;50\;Torr$. There are some interfacial reactions in the as-grown films with impurities of mostly $Mg_2Si$, $MgAl_2O_4$, and other phases. The $T_c$'s of $MgB_2$ films were observed to be as high as 39 K, but the transition widths were increased with growth temperatures. The magnetization was measured as a function of temperature down to the temperature of 5 K, but the complete Meissner effect was not observed, which shows that the granular nature of weak links is prevailing. The formation of mostly $Mg_2Si$ impurity in HPCVD process is discussed, considering the diffusion and reaction of Mg vapor with silicon substrates.

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