Self‐Organized Epitaxial Vertically Aligned Nanocomposites with Long‐Range Ordering Enabled by Substrate Nanotemplating

Abstract

Vertically aligned nanocomposites (VAN) thin films present as an intriguing material family for achieving novel functionalities. However, most of the VAN structures tend to grow in a random fashion, hindering the future integration in nanoscale devices. Previous efforts for achieving ordered nanopillar structures have been focused on specific systems, and rely on sophisticated lithography and seeding techniques, making large area ordering quite difficult. In this work, a new technique is presented to produce self-assembled nanocomposites with long-range ordering through selective nucleation of nanocomposites on termination patterned substrates. Specifically, SrTiO (001) substrates have been annealed to achieve alternating chemical terminations and thus enable selective epitaxy during the VAN growth. La Sr MnO :CeO (LSMO):CeO nanocomposites, as a prototype, are demonstrated to form well-ordered rows in matrix structure, with CeO (011) domains selectively grown on SrO terminated area, showing enhanced functionality. This approach provides a large degree of long-range ordering for nanocomposite growth that could lead to unique functionalities and takes the nanocomposites one step closer toward future nanoscale device integration.

Self‐Assembled Ordered Three‐Phase Au–BaTiO3–ZnO Vertically Aligned Nanocomposites Achieved by a Templating Method

“…However, due to the availability of a limited range of structures in terms of crystallinity and morphology, a greater design flexibility and a structural complexity along with versatile growth techniques are needed for developing next generation integrated photonic and electronic devices. [18] In contrast, a self-assembly approach for fabricating such ordered oxide-metal nanocomposites is costeffective and overcomes the resolution limitation and complex fabrication steps. Previous efforts to grow ordered ceramicmetal nanocomposites have focused on applying patterning techniques such as anodized alumina oxide (AAO) templates, [15] e-beam lithography, [16] focused ion beam (FIB), [17] and substrate nanotemplate.…”

Three-dimensional strain engineering in epitaxial vertically aligned nanocomposite thin films with tunable magnetotransport properties

“…5e). 26,36,38,43,[45][46][47][48][49][50][51][52] The relatively lower MR% in C2 and C3 compared to C1 is possibly related to the surface roughness observed in both samples where the 3D insulating framework might not be effective in the top layers. The L1-L3 samples with a 3D LSMO framework exhibit a metallic behavior in contrast to the C1-C3 samples (Fig.…”

“…1), as well as its high thermal/mechanical stability. 26,36,38 Furthermore, CeO 2 can serve as the insulating layer favoring spin-dependent tunneling, and is easier to explore the synergistic effects between strain tuning and the LFMR effect.…”

Ordered Structures with Functional Units as a Paradigm of Material Design

“…Controlling the selective growth of functional units on the substrates is beneficial for device integration. To address this challenge, researchers at Texas A&M University reported the selective growth of LSMO:CeO 2 ordered films on (001) SrTiO 3 (STO) substrates by selective nucleation on termination patterned substrates ( Figure ) . Through the preheat treatment at high‐temperature, SrO and TiO 2 alternately parallel steps were formed on STO substrates.…”

“…La 0.7 Sr 0.3 MnO 3 (LSMO): CeO 2 composite films: a) random growth and b) template‐induced ordered growth. a,b) Reproduced with permission . Copyright 2017, Wiley‐VCH.…”