Hydrostatic and Biaxial Strain in BaxSr1-xTiO3Films Grown by Pulsed Laser Deposition

Abstract

AbstractWe grew BaxSr1−xTiO3(BST) films on MgO single crystal substrates by pulsed laser deposition (PLD). We report the in-plane (a) and out-of-plane (c) lattice parameters of BST films deposited in a range of O2deposition pressures [P(02)], as measured by asymmetric rocking curve diffraction. As P(O2) increases, the films' biaxial strain changes from compression (a<c), to cubic (a=c), and then to tension (a>c). Furthermore, bothaandcare larger than the lattice constant for bulk BST of the same composition. This indicates the presence of a hydrostatic strain component in addition to the biaxial component. From the measured lattice parameters, we calculate the total residual strain in terms of biaxial and hydrostatic components. We also examine the effects of a post-deposition anneal. Characterizing residual strain and understanding its origin(s) are important since strain affects the dielectric properties of BST films and thereby the properties of devices which incorporate them.