Effect of copper-oxide segregation on the dielectric properties of CaCu3Ti4O12 thin films fabricated by pulsed-laser deposition
- Effect of copper-oxide segregation on the dielectric properties of CaCu3Ti4O12 thin films fabricated by pulsed-laser deposition
- 이성윤; 김영환; 최경진; 정성목; 유상임
- CaCu3Ti4O12 (CCTO); Pulsed laser deposition; Dielectric constant and loss; Copper-oxide segregation
- Issue Date
- Thin solid films
- VOL 518, NO 20, 5711-5714
- We investigated the effects of post-deposition cooling conditions on the surface morphologies and dielectric
properties of CaCu3Ti4O12 (CCTO) thin films grown by pulsed-laser deposition on Pt/TiO2/SiO2/Si substrates.
CCTO thin films cooled under the typical cooling parameters, i.e., slow cooling (3 °C/min) at high oxygen
pressure (66 kPa) showed a severe segregation of nanoparticles near the grain boundaries, which was
identified to be copper oxide from electron probe micro analyzer mapping. On the other hand, we could not
observe any segregation on the film surface when the samples were cooled fast (∼20 °C/min) at relatively
low oxygen pressure (100 Pa). The dielectric constant, εr, of CCTO thin films deposited at 750 °C with severe
surface segregation (εr∼750 at 10 kHz) was found to be much lower than that (εr ∼ 2000 at 10 kHz) of CCTO
thin films with smooth surface. As the copper-oxide segregation becomes more serious, which preferentially
occurs at relatively high ambient oxygen pressure and temperature, the degradation in the dielectric
properties of CCTO films becomes larger. The variation of dielectric constant of CCTO films with no copperoxide
segregation could be related to the presence of an impurity phase at grain boundaries.
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