Effect of Li substitution on dielectric and ferroelectric properties of ZnO thin films grown by pulsed-laser ablation

被引:53
作者
Dhananjay
Nagaraju, J
Krupanidhi, SB [1 ]
机构
[1] Indian Inst Sci, Dept Instrumentat, Bangalore 560012, Karnataka, India
[2] Indian Inst Sci, Mat Res Ctr, Bangalore 560012, Karnataka, India
关键词
D O I
10.1063/1.2169508
中图分类号
O59 [应用物理学];
学科分类号
摘要
Li-doped ZnO thin films (Zn1-xLixO, x=0.05-0.15) were grown by pulsed-laser ablation technique. Highly c-axis-oriented films were obtained at a growth temperature of 500 degrees C. Ferroelectricity in Zn1-xLixO was found from the temperature-dependent dielectric constant and from the polarization hysteresis loop. The transition temperature (T-c) varied from 290 to 330 K as the Li concentration increased from 0.05 to 0.15. It was found that the maximum value of the dielectric constant at T-c is a function of Li concentration. A symmetric increase in memory window with the applied gate voltage is observed for the ferroelectric thin films on a p-type Si substrate. A ferroelectric P-E hysteresis loop was observed for all the compositions. The spontaneous polarization (P-s) and coercive field (E-c) of 0.6 mu C/cm(2) and 45 kV/cm were obtained for Zn0.85Li0.15O thin films. These observations reveal that partial replacement of host Zn by Li ions induces a ferroelectric phase in the wurtzite-ZnO semiconductor. The dc transport studies revealed an Ohmic behavior in the lower-voltage region and space-charge-limited conduction prevailed at higher voltages. The optical constants were evaluated from the transmission spectrum and it was found that Li substitution in ZnO enhances the dielectric constant. (c) 2006 American Institute of Physics.
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页数:6
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