Ferroelectricity in Li-implanted ZnO thin films |
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| Authors: | C.W. Zou M. Li M.L. Yin L.P. Guo T.W. Kang |
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| Affiliation: | a Accelerator Laboratory, Department of Physics and Key Laboratory of Acoustic Photonic Materials and Devices of Ministry of Education, Wuhan University, Wuhan 430072, China
b Quantum Functional Semiconductor Research Center, Dongguk University, Seoul 100-715, Republic of Korea |
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| Abstract: | ZnO:Li thin films were prepared by implantation of ZnO with a Li ion fluence 5 × 1016 ions/cm2 at implantation energies of 50, 100, 200 keV. Ferroelectric characterization of the implanted samples revealed a clear hysteresis in the polarization-field curves. The origin of the ferroelectricity can be attributed to an off-center dipole caused by the large difference in ionic radii between the host Zn (0.74 Å) and the dopant Li (0.60 Å). ZnO:Li films which were implanted at 200 keV and annealed at a temperature of 700 °C exhibited a well-defined polarization hysteresis loop, with a remanent polarization of 0.8 μC/cm2 and coercive field of 8.2 kV/cm, at room temperature. The dielectric phase transition was observed in the temperature range from 340 to 360 K. It is concluded that this novel ferroelectric phase transition in ZnO:Li results from the small structural distortion induced along the c-axis. |
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| Keywords: | 73.40Sx 73.50-h 73.61Ga |
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