"Nanometer-scale epitaxial strain release in perovskite heterostructures using “SrAlOx” sliding buffer layers "

H. K. Sato: J. A. Mundy, T. Higuchi, Y. Hikita, C. Bell, D. A. Muller, and H. Y. Hwang ; Appl. Phys. Lett., 04/25/11.

Additional Authors: J. A. Mundy, T. Higuchi, Y. Hikita, C. Bell, D. A. Muller, and H. Y. Hwang

Abstract:

We demonstrate the strain release of LaAlO3 epitaxial films on SrTiO3 (001) by inserting ultrathin “SrAlOx” buffer layers. Although SrAlOx is not a perovskite, nor stable as a single phase in bulk, epitaxy stabilizes the perovskite structure up to a thickness of 2 unit cells (uc). At a critical thickness of 3 uc of SrAlOx, the interlayer acts as a sliding buffer layer, and abruptly relieves the lattice mismatch between the LaAlO3 film and the SrTiO3 substrate, while maintaining crystallinity. This technique may provide a general approach for strain relaxation of perovskite films far below the thermodynamic critical thickness.