$n-GaAs$ quality diagnose from shallow impurities photoelectric   spectroscopy line shapes dependence on electric field
  It is established experimentally that the low temperature photoelectric spectra line width of shallow impurities depends not only on charged impurity concentration $N_i=2KN_A$ and degree of samples compensation $%   K=N_A/N_D$, as it was believed earlier.To a great extent it depends on the impurity distribution inhomogeneity also.For samples with homogeneous and inhomogeneous distribution of impurities line width dependence character on external electric fields, smaller than break down one, are different.This broadening mechanism allows to control the quality of samples with nearly equal impurity concentrations. 
O.Z.Alekperov