Hostname: page-component-78c5997874-fbnjt Total loading time: 0 Render date: 2024-11-14T07:14:56.330Z Has data issue: false hasContentIssue false
  • English
  • Français

Growth kinetics of MgB2 layer and interfacial MgO layer during ex situ annealing of amorphous boron film

Published online by Cambridge University Press:  01 October 2004

Hyun-Mi Kim ,
Sung-Soo Yim ,
Ki-Bum Kim ,
Seung-Hyun Moon ,
Young-Woon Kim  and
Dae-Hwan Kang
Hyun-Mi Kim
Affiliation:
School of Materials Science and Engineering and Nano Systems Institute-National Core Research Center, Seoul National University, Seoul 151-742, Korea
Sung-Soo Yim
Affiliation:
School of Materials Science and Engineering and Nano Systems Institute-National Core Research Center, Seoul National University, Seoul 151-742, Korea
Ki-Bum Kim*
Affiliation:
School of Materials Science and Engineering and Nano Systems Institute-National Core Research Center, Seoul National University, Seoul 151-742, Korea
Seung-Hyun Moon
Affiliation:
School of Materials Science and Engineering, Seoul National University, Seoul 151-742, Korea
Young-Woon Kim
Affiliation:
School of Materials Science and Engineering, Seoul National University, Seoul 151-742, Korea
Dae-Hwan Kang
Affiliation:
Korea Institute of Science and Technology, Thin Film Materials Research Center, Seoul 136-791, Korea
*
a) Address all correspondence to this author. e-mail: kibum@snu.ac.kr
Get access

Abstract

This paper describes the growth kinetics of an interfacial MgO layer as well as those of an MgB2 layer during ex situ annealing of the evaporated amorphous boron (a-B) film under Mg vapor overpressure. A thin MgO layer is formed at the interface between a-B and Al2O3 substrate before the formation of crystalline MgB2 layer and the interfacial layer is epitaxially related with Al2O3 substrate (MgO (111)[110] // Al2O3 (0001)[1100]). The interfacial MgO layer continues to grow during the annealing, and its apparent growth rate is about 0.1 nm/min. The analysis of MgB2 layer growth kinetics using cross-sectional transmission electron microscopy reveals that there exist two distinct growth fronts at both sides of an MgB2 layer. The growth kinetics of the lower MgB2 layer obeys the parabolic rate law during the entire annealing time. The growth of the upper MgB2 layer is controlled by the surface reaction between out-diffused boron and Mg vapor up to 10 min, resulting in a rough surface morphology of MgB2 layer. By considering the mass balance of Mg and boron during ex situ annealing, we obtained the diffusivities of Mg and boron in MgB2 layer which were in the same order range of approximately 10−12 cm2/s.

Keywords

SuperconductorKineticsTransmission electron microscopy (TEM)
Type
Articles
Information
Journal of Materials Research , Volume 19 , Issue 10 , October 2004 , pp. 3081 - 3089
Copyright
Copyright © Materials Research Society 2004

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1Kim, H.M., Yim, S.S., Kim, K.B., Kang, D.H., Moon, S.H., Kim, Y.W. and Lee, H.N.: The reaction sequence and microstructure evolution of an MgB2 layer during ex situ annealing of amorphous boron film. J. Mater. Res. 19, 409 (2004).Google Scholar
2Li, D.X., Pirouz, P., Heuer, A.H., Yadavalli, S. and Flynn, C.P.: A high-resolution electron microscopy study of MgO/Al2O3 interfaces and MgAl2O4 spinel formation. Philos. Mag. A 65, 403 (1992).CrossRefGoogle Scholar
3Bu, S.D., Kim, D.M., Choi, J.H., Giencke, J., Hellstrom, E.E., Larbalestier, D.C., Patnaik, S., Cooley, L., Eom, C.B., Lettieri, J., Schlom, D.G., Tian, W. and Pan, X.Q.: Synthesis and properties of c-axis oriented epitaxial MgB2 thin films. Appl. Phys. Lett. 81, 1851 (2002).Google Scholar
4Tian, W., Pan, X.Q., Bu, S.D., Kim, D.M., Choi, J.H., Patnaik, S. and Eom, C.B.: Interfacial structure of epitaxial MgB2 thin films grown on (0001) sapphire. Appl. Phys. Lett. 81, 685 (2001).CrossRefGoogle Scholar
5Deal, B.E. and Grove, A.S.: General relationship for the thermal oxidation of silicon. J. Appl. Phys. 36, 3770 (1965).CrossRefGoogle Scholar
6Massalski, T., Binary Alloy Phase Diagram, 2nd ed. (ASM International, Materials Park, OH).Google Scholar
7McCarty, L.V., Kasper, J.S., Horn, F.H., Decker, B.F. and Newkirk, A.E.: A new crystalline modification of boron. J. Am. Chem. Soc. 80, 2592 (1958).CrossRefGoogle Scholar
8Guette, A., Barret, M., Naslain, R., Hagenmuller, P., Tergenius, L-E. and Lundstrom, T.: Crystal structure of magnesium heptaboride Mg2B14. J. Less-Common Met. 82, 325 (1981).CrossRefGoogle Scholar
9Kobayashi, M., Higashi, I. and Takami, M.: Fundamental structure of amorphous boron. J. Solid State Chem. 133, 211 (1997).CrossRefGoogle Scholar
10Greenwood, N.N. and Thomas, B.S.: The Chemistry of BORON (Pergamon Press, Oxford, U.K., 1973).Google Scholar
11Will, G., Kirfel, A., Gupta, A. and Amberger, E.: Electron density and bonding in B13 C2. J. Less-Common Met. 67, 19 (1979).Google Scholar
12Kasper, J.S., Vlasse, M. and Naslain, R.: The alpha-AlB12 structure. J. Solid State Chem. 20, 281 (1977).CrossRefGoogle Scholar
13Tu, K-N., Mayer, J.W. and Feldman, L.C.: Electronics Thin Film Science for Electrical Engineers and Materials Scientists (Macmillan Publishing Company, 1992).Google Scholar