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Vol.41, No.6, 362 ~ 369, 2003
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| Title |
| Mechanisms of Misfit Strain Relaxation in Epitaxially Grown BLT (Bi4-xLaxTi3O12, x=0.75) thin Films |
| 김형석 H. S. Kim , 오상호 S. H. Oh , 서주형 J. H. Suh , 박찬경 C. G. Park |
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| Abstract |
| Mechanisms of misfit strain relaxation in epitaxially grown Bi_4-χLa_χTi_3O_12 (BLT) thin films deposited on SrTiO_3 (STO) and LaAlO_3(LAO) substrates have been investigated by means of transmission electron microscopy (TEM). The misfit strain of 20 nm thick BLT films grown on STO substrate was relaxed by forming misfit dislocations at the interface. However, cracks were observed in 100 nm thick BLT films grown on the same STO. It was confirmed that cracks were formed because of high misfit strain accumulated with increasing the thickness of BLT, which was not sufficiently relaxed by misfit dislocations. In the case of the BLT film grown on LAO substrate, the magnitude of lattice misfit between BLT and LAO was very small (∼1/10) in comparison with the case of the BLT grown on STO. The relatively small misfit strain formed in layered structure of the BLT films on LAO, therefore, was easily relaxed by distorting the film, rather than forming misfit dislocations or cracks, resulting in misorientation regions in the BLT film. |
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| Key Words |
| BLT, Epitaxial growth, Misfit strain, Transmission electron microscopy, TEM |
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