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Metal–insulator transition in manganese‐doped InSb crystals
Author(s) -
Obukhov S. A.
Publication year - 2005
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.200440008
Subject(s) - condensed matter physics , impurity , hall effect , manganese , electrical resistivity and conductivity , doping , metal–insulator transition , band gap , semiconductor , materials science , activation energy , conductivity , magnetic semiconductor , chemistry , metal , analytical chemistry (journal) , physics , metallurgy , optoelectronics , organic chemistry , quantum mechanics , chromatography
Transport properties of manganese‐doped InSb crystals with hole concentration close to the critical concentration N cr of the metal–insulator transition (MIT) in p‐InSb(Mn) was found to be different from MIT in semiconductors doped with non‐magnetic impurities such as p‐Ge(Ga), p‐Si(P) and p‐InSb(Ge). On the insulator side of the transition ( N Mn ≤ N cr = 2 × 10 17 cm –3 ) in the range of hole concentration p = 1–2 × 10 17 cm –3 an activation type of conductivity with energy gap Δ = 7 × 10 –6 –10 –3 eV was observed. Thus, the usually observed variable range hopping conductivity in crystal semiconductors doped with non‐magnetic impurities at low and super‐low temperatures was not revealed in p‐InSb(Mn) at p ≤ N cr . An external magnetic field decreased Δ and caused a giant decrease of specific resistivity ( ρ 0 / ρ B ∼ 10 4 at T ≤ 0.3 K and B ≥ 3 T). On cooling to temperatures below T = 1.5 K the Hall constant changed sign at B < 3 T. The change of Hall constant sign with decrease of temperature means that conductivity of p‐InSb(Mn) and crystals compensated with Te – p‐InSb(Mn, Te) – at low temperatures was caused by electrons. The proposed model associated an activation energy Δ at p ∼ N cr with the energy gap between sub‐bands formed in the impurity band. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)