Defects in (La_(0.7)Sr_(0.3)Mno_3/SrTiO_3)_(15) superlattices grown by pulsed injection MOCVD

摘要

(La_(0.7)Sr_(0.3)MnO_3/SrTiO_3)_(15) superlattices were grown in situ by liquid-injection metal-organic chemical vapour deposition on (001)LaAlO_3 and (001)SrTiO_3 substrates. Defects in these superlattices were studied by X-ray texture diffractornetry 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 (001) 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_(0.7)Sr_(0.3)MnO_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.