Atomic Heterointerfaces and Electrical Transportation Properties in Self-Assembled LaNiO3–NiO Heteroepitaxy

Abstract

Vertical nanostructure heteroepitaxy opens new opportunities for designing next-generation electronic devices due to the enthralling multifunction combi-nations and the abundant heterointerfaces manipulated effects. In this study, self-assembled heteroepitaxial thin flms, vertically aligned metallic LaNiO₃ (LNO) and semiconducting NiO with diverse heterointerfaces, are created and systematically investigated by advanced transmission electron microscopy. With the increase of LaNiO₃ content, the LaNiO3 phases present as isolated islands encircled by the connected NiO nanoplates and eventually become the continuous matrix with embedded NiO nanopillars. The atomic heterointer-face between NiO and LaNiO₃ phases is determined to be [NiO₂–LaO]LaNiO₃–LaO–[NiO]NiO, in which an extra La–O layer is enriched at the heterointerface. Besides, the formation mechanism of the heterointerface and antiphase boundaries observed in LaNiO₃ phase is discussed. The electrical transport properties at room temperature can be tuned gradually by changing the volume ratio of constituents. The correlation among the insulator-to-metal transition, the carrier types associated with transport behaviors, and the heterostructure evolutions are explored. This study offers a desirable platform to design new multifunctional electronic devices based on the oxide heterojunctions.