Undoped Semi-Insulating GaAs of Very Low Residual Acceptor Concentration

摘要: We have studied undoped GaAs of shallow acceptor concentrations close to and below 51014cm-3. After ingot annealing with slow cooling rate this material shows resistivity values 107 Ωcm, spanning several orders magnitude. By an additional procedure these can be raised some Ωcm. DLTS results are presented indicating that the electrical characteristics in annealed state governed by uncompensated deep donors shallower than EL2, mainly EL6 near Ec -0.35 eV. a drastic decrease concentration is observed, which explains rise resistivity. This confirmed theoretical calculation dependence EL2 net compensation ratio, agrees quantitatively experimental values.