Microstructure and residual strain in La{sub 2}CuO{sub 4} thin films on LaSrAlO{sub 4}-buffered SrTiO{sub 3} substrates
The microstructure and residual strain of bilayer films of La{sub 2}CuO{sub 4}/LaSrAlO{sub 4} on SrTiO{sub 3} substrates are investigated by means of electron-diffraction analysis and high-resolution transmission electron microscopy. In two samples containing LaSrAlO{sub 4} buffer layers with thicknesses of 37 and 75 nm, a compressive strain is measured in the La{sub 2}CuO{sub 4} layers. From the presence of lattice defects close to interface imperfections it can be concluded that the thickness of these La{sub 2}CuO{sub 4} layers is close to the critical value for mismatch-strain relaxation. The strain level in the layer on the 37-nm-thick buffer is lower than that in the layer on the 75-nm buffer. A high density of planar shear defects is observed which can be introduced by steps of the substrate surface and by stacking faults in the film. Interfacial stacking faults are found at the interface between the La{sub 2}CuO{sub 4} and the LaSrAlO{sub 4} layers. Interface roughening can hinder the formation of these faults. In addition, a strong roughness of the interface is found to induce strong lattice bending and extra strain in the La{sub 2}CuO{sub 4} layer.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40230889
- Journal Information:
- Physical Review B, Vol. 64, Issue 7; Other Information: DOI: 10.1103/PhysRevB.64.075416; Othernumber: PRBMDO000064000007075416000001; 008131PRB; PBD: 15 Aug 2001; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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