Defects in (La 0.7Sr 0.3Mno 3/SrTiO 3) 15 superlattices grown by pulsed injection MOCVD

Abstract

(La 0.7Sr 0.3MnO 3/SrTiO 3) 15 superlattices were grown in situ by liquid-injection metal-organic chemical vapour deposition on (0 0 1)LaAlO 3 and (0 0 1)SrTiO 3 substrates. Defects in these superlattices were studied by X-ray texture diffractometry and by transmission electron microscopy. Two types of defects were identified: (i) defects with feather-like and inverse pyramidal shapes and with particular crystallographic orientational relationships with respect to the epitaxial (0 0 1) superlattice, and (ii) defects with an inverse pyramidal shape but of the same crystallographic orientation as the epitaxial superlattice. Both these defects originate from nucleus observed either on La 0.7Sr 0.3MnO 3 or SrTiO 3 layers. They propagate across the following deposited layers and create dots at the surface of the multilayer structure. Whether a nucleation and growth of these defects could be controlled then a new process for producing 2D periodic arrays of dots could be envisaged for photonic applications.