The analysis on the origin of high resistivity in Cl‐doped polycrystalline CdZnTe thick films

Polycrystalline CdZnTe thick films were grown by thermal evaporation method using CdZnTe and CdZnTe:Cl source. Non-doped CdZnTe thick films have Te-rich stoichiometry having resistivity 3.3 × 109 Ωcm. The Cl-doped CdZnTe thick films have 1.2 × 1010 Ωcm in resistivity. To evaluate the role of Cl in the increasement of the resistivity, the density of localized states were calculated from the analysis of transient TOF (time of flight)current. From the comparison of Cl-doped CZT thick films with non-doped and O2 annealed CdZnTe thick films, we have found that Cl doping is related to the formation of states at EV + 0.75 eV region and oxygen reduces grain boundary related defects through formation TeO2 or CdTeO3. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)