Crystal synthesis and effects of epitaxial perovskite manganite underlayer conditions on characteristics of ZnO nanostructured heterostructures

Abstract

This study presents the synthesis of high-density aligned wurtzite ZnO nanostructures using thermal evaporation on perovskite (La,Sr)MnO₃(LSMO) epitaxy to form a heterostructure without the assistance of metallic catalysis. LSMO epitaxial films are RF-sputtered with various crystal qualities to examine the correlation between the interface and electrical characteristics of the heterostructures. The ZnO nanostructures–LSMO epitaxial heterostructures show electrical rectifying behavior without inserting an ultrathin insulating layer at the hetero-interface. Misfit strain, intrinsic strain, and crystal defects are major factors in causing a phase separation in the as-prepared manganite LSMO epitaxial films. The coexistence of a charge-ordered insulating domain and a ferromagnetic metallic domain causes inhomogeneous electrical contact at the ZnO–LSMO heterointerfaces, further deteriorating the junction characteristics. A high-temperature annealing procedure and moderate LSMO epitaxy film thickness are required for the construction of an efficient ZnO nanostructures–LSMO epitaxy junction.