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Quasi‐two‐dimensional superconductivity in wurtzite‐structured InN films
Author(s) -
Ling D. C.,
Cheng J. H.,
Lo Y. Y.,
Du C. H.,
Chiu A. P.,
Chang C. A.,
Chang P. H.
Publication year - 2007
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200777396
Subject(s) - wurtzite crystal structure , condensed matter physics , critical field , superconductivity , magnetoresistance , metalorganic vapour phase epitaxy , scattering , anisotropy , materials science , sapphire , chemistry , physics , layer (electronics) , nanotechnology , crystallography , hexagonal crystal system , magnetic field , epitaxy , optics , laser , quantum mechanics
C ‐axis oriented InN films with wurtzite structure were grown on sapphire (0001) substrate by MOCVD method. Superconductivity with transition onset temperature T c,onset around 3.5 K has been characterized by magnetotransport measurements in fields up to 9 Tesla for films with carrier concentration in the range of 1×10 19 cm –3 to 7×10 20 cm –3 . Among them, the film with a nitridation buffer layer has the highest zero‐resistance temperature T c0 of 2 K. The normal‐state magnetoresistance follows Kohler's rule Δ R / R ∝ ( H / R ) 2 , indicating that there is a single species of charge carrier with single scattering time at all points on the Fermi surface. The extrapolated value of zero‐temperature upper critical field H c 2 ab (0) and H c 2 c (0) is estimated to be 5900 G and 2800 G, respectively, giving rise to the anisotropy parameter γ about 2.1. The angular dependence of the upper critical field is in good agreement with the behavior predicted by Lawrence‐Doniach model in the two‐dimensional (2D) limit strongly suggesting that the InN film is a quasi‐2D superconductor. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)