Strain relaxation analysis of LaAlO3/SrTiO3 heterostructure using reciprocal lattice mapping

Strain-relaxation in LaAlO3/SrTiO3 heterostructures was systematically investigated with LaAlO3 film thickness in the range 4.9-84 nm. Heterostructures were characterized using reciprocal lattice mapping (RLM), high resolution rocking curve, and x-ray reflectivity. RLM enables the measurement of lattice constant with accuracy of 10(-6) nm. Lattice constant, mismatch, and strain are independently determined in both out-of-plane and in-plane directions. Heterostructures are tetragonally distorted over the entire range of film thickness, even in the film with thickness of 84 nm, in which plastic deformation occurred. This strain-relaxation analysis of LaAlO3/SrTiO3 heterostructure contributes, on the experimental basis, to the knowledge of the strained heterostructure interfaces from thin film growth point of view. (C) 2012 American Institute of Physics. [doi:10.1063/1.3685463]