ELECTRICAL PROPERTIES OF CZTS THIN FILMS GROWN BY COEVAPORATION AND ITS RELATION WITH SECONDARY PHASE FORMATION

摘要

The relation of the electrical transport properties of Cu_2ZnSnS_4 (CZTS) thin films prepared by co-evaporation with secondary phases formation was investigated trough measurements of photoconductivity and conductivity as a function of the temperature. From temperature dependent electrical conductivity measurements it was found that at temperatures greater than 600K, the electrical conductivity is dominated by band conduction and at lower temperatures, Mott variable-range hopping (VRH) is observed. On the other hand, photocurrent studies revealed that successive slow photoresponse transient following after a fast rise is due to the establishment of equilibrium between the charge carriers in the conduction band and the trapping centers generated by native defects in the CZTS films. By using the real part of Fourier transform, the experimental curves of photocurrent rise have been analyzed and time constants and amplitudes were estimated.