Band Gap and Band Tailing Behaviour of PLZT Films

Abstract

Lanthanum modified lead zirconate titanate (PLZT) thin films were fabricated on sapphire (0001) substrate by sol-gel method. The cell parameters of films were calculated with help of whole pattern fitting procedure. The study of optical properties revealed the fractal behaviour of absorption coefficient near the absorption edge. The strong shift of the absorption edge in thin films in comparison with bulk PLZT was observed. This shift could not be caused just by the presence of the strain. The increased disorder and polarization fluctuations were suggested as the additional reason that was supported by nearly twice higher value of the exponential tail width in the films in comparison with bulk PLZT.

Keywords:

• PLZT
• sol-gel process
• optical and structure properties

Acknowledgments

The authors would like to thank Prof. A. Sternberg, Dr. M. Dambekalne, Mg. M. Antonova and Mg. M. Livinsh for preparation of bulk PLZT ceramic. This work was supported by FCT (Portugal) under the project SFRH/BPD/11675/2002.