Off-centered polarization and ferroelectric phase transition in Li-doped ZnO thin films grown by pulsed-laser ablation

Kekuda, Dhananjaya and Nagaraju, J and Krupanidhi, S B (2007) Off-centered polarization and ferroelectric phase transition in Li-doped ZnO thin films grown by pulsed-laser ablation. Journal of applied Physics, 101.

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Abstract

Li-doped ZnO _Zn1−xLixO, x=0.15_ thin films have been grown on platinum-coated silicon substrates via pulsed-laser ablation. The films were grown at fixed substrate temperature of 500 °C and different partial pressure of oxygen _PO2_100–300 mTorr_. The films showed _002_ preferred orientation. The doping concentration and built-in potential were estimated from the capacitance-voltage characteristics. In order to investigate the phase transition behavior of the films,dc conductivity and dielectric measurements were conducted. The phase transition temperature was found to be 330 K. The activation energy _dc_ has been found to be 0.05 and 0.28 eV in ferroelectric and paraelectric phases, respectively. The Zn0.85Li015O thin films exhibited well-defined polarization hysteresis loop, with a remanent polarization of 0.2 _C/cm2 and coercive field of 25 kV/cm, at room temperature. The conduction mechanism of the laser ablated Zn0.85Li015O films was analyzed in the light of impedance spectroscopy.

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