The spectra of the optical absorption coefficient in low absorption region are obtained by using anormalization procedure for the photoconductivity spectra.The results are explained in terms of theoptical transition of electrons from localized states in the exponential valence band tail and in danglingbond states 1.0 eV below the conduction band edge to extended conduction band states.Then thedensity of the gap states below the Fermi level E_F is obtained.From the investigation ofrecombination kineties,the average density of,the gap states over the range of(F_(F_n)-E_F)and thedensity of the gap states above the Fermi level E_F are obtained.These indicate that the width of theconduction band tail is smaller than that of the valence band tail. The spectra of the optical absorption coefficient in low absorption region are obtained by using anormalization procedure for the photoconductivity spectra. The results were explained in terms of the optical transition of electrons from localized states in the exponential valence band tail and in dangling bond states 1.0 eV below the the conduction band edge to extended conduction band states. The intensity of the gap states below the Fermi level E_F is obtained. From the investigation of recombination kineties, the average density of, the gap states over the range of (F_ (F_n) -E_F) and the intensity of the gap states above the Fermi level E_F are obtained. the sense that the width of theconduction band tail is smaller than that of the valence band tail.