Deep level defects in porous silicon

This paper reports on the existence of deep level defects in the band gap of porous silicon by the photo-induced current transient spectroscopy technique combined with the results of thermovoltage and conductivity measurements. The defects are found to exhibit deep donor levels in the upper part of the band gap. It is found that the thermal emission and ionization energies of the defect increase in the range from 0.29 to 0.86 eV below the conduction band edge as the porosity increases, and it is proposed that the defects play the role of a luminescence killer.