Screening Effect in a Disordered Electron System. II. Application to the Impurity Band

The screening effect is included into the Klauder-Yonezawa model of impurity band conduction at zero temperature. It is shown that the binding energy of impurity potential goes to zero smoothly with the increase of the concentration of impurities, which differs from the result of Li, Love and Miller and coincides with the suggestion of Krieger. The screening effect on the vallue of the mobility is in good agreement with experiments on InSb at comparatively low concentrations. It is also shown that the model is not good at high concentrations, which is demonstrated by the calculation of the dielectric function and by the comparison of the mobility with experiments on InSb. Effective mass of the impurity band is defined by the frequency dependent conductivity.