Photo-induced current transient spectroscopy studies on polycrystalline CdTe

Polycrystalline CdTe samples were characterized using photo-induced current transient spectroscopy (PICTS). The spectra obtained show that the traps are not discrete ones, or localized bands in the gap like in monocrystalline samples, indeed the PICTS signal presents large peaks. With an improvement of the calculation method presented here, these spectra reveal two types of traps. The first ones are active at low temperature and have energies between 0.3 and 0.5 eV. The second ones are deep level traps located between 0.65 and 0.8 depending on the sample. Focusing on these deep level traps, their influence on the photoconductive response of the material is discussed.