Structure of the Impurity Band and Magnetic‐Field‐Induced Metal‐Non‐Metal Transition in n‐Type InSb

Several samples of n‐type indium antimonide in the doping range 5.7 × 1013 to 3.9 × × 1014 cm−3 donors have been investigated. The electrical resistivity has been measured from 1.6 to 4.2 °K in magnetic fields up to 5 T. Activation energies ϵ1, ϵ2, ϵ3 which are characteristic of the resistivity versus temperature curves are measured and their variation with magnetic field are investigated. A transition from metallic conduction to an activated conduction process is observed for a critical magnetic field the value of which increases with the concentration of impurities. These features are interpreted with an impurity band structure which varies when the magnetic field is increased. A model of the impurity band and its changes with magnetic field are suggested. This model is consistent with the ideas of Mott and Davis on impurity conduction and the D− band model of Fritzsche suggested by Hubbard. These results are comparable with those which have already been obtained in germanium and silicon when the magnetic field or impurity concentrations are varied.