Correlation between the stress in ZnO thin films and the Urbach band tail width

Abstract A comparison of the changes in the optical and structural properties of ZnO thin films, undoped and doped with Al, Er and Ta, deposited by magnetron co‐sputtering in Ar is performed in this work. A set of ZnO samples deposited by sputtering in Ar+H 2 is studied, as well. The films are deposited at different substrate temperatures and with different concentrations of the doping elements. The band gap energy and the Urbach band tail parameter are calculated from the spectral dependence of the coefficient of absorption. The stresses in the films are calculated from X‐ray diffraction patterns. A correlation between the band tail widths and the stress in the ZnO thin films is observed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)