Magnetic freeze-out and impurity band conduction in n-InSb

Non-ohmic conduction of n-InSb with different donor concentrations (Nd=2×1014–View the MathML source) in perpendicular magnetic fields has been measured at low temperatures, in order to infer the impurity band mobility μi with the aid of the two-band analysis. The decrease of μi with increasing magnetic fields has been found to reflect exactly the shrinkage of donor wave functions due to magnetic field and the magnetic-field induced metal–insulator transition is an event in the impurity band. The temperature dependence of μi in moderate magnetic fields above the transition field Bc appears to obey the Mott variable-range hopping law as View the MathML source with x=1/4.