Universal Fabrication of Graphene/Perovskite Oxide Hybrid Heterostructures

TL;DR

This paper introduces a universal, catalyst-free atmospheric chemical vapor deposition method for directly growing high-quality graphene on various insulating perovskite oxide substrates, enabling defect-free hybrid heterostructures with potential for advanced functionalities.

Contribution

It presents the first universal, transfer-free growth process for graphene on insulating substrates using perovskite oxides, with optimized conditions applicable across different materials.

Findings

Successful direct growth of monolayer graphene on multiple perovskite oxides.

Growth temperature critically affects graphene quality and multilayer formation.

Substrate-induced lattice-phonon and electron-phonon interactions observed.

Abstract

Hybrid heterostructures composed of graphene and perovskite oxides provide a promising platform for exploiting synergetic interfacial functionalities. Conventional fabrication methods of the hybrid heterostructures rely on transferring graphene grown on metallic substrates-- a process that is time-consuming, labor-intensive, and prone to introducing numerous defects. In this study, we present a universal, catalyst-free method for the direct growth of graphene on insulating substrates by employing three different perovskite oxide substrates (SrTiO$_3$, LaAlO$_3$, and (La$_{0.18}$Sr$_{0.82}$)(Al$_{0.59}$Ta$_{0.41}$)O$_3$) using atmospheric chemical vapor deposition. Comprehensive characterization via Raman spectroscopy, X-ray spectroscopy, scanning probe microscopy, and electron microscopy confirmed the formation of a uniform, continuous monolayer graphene on all substrates. We identified that growth temperature critically governs graphene quality, as excessive active species may lead to secondary nucleation and the formation of multilayer graphene. Notably, all substrates shared the same optimal growth conditions. Low-temperature Raman spectroscopy and scanning tunneling microscopy of the graphene/SrTiO$_3$ hybrid heterostructure revealed cooperative phenomena, including substrate-induced lattice-phonon and electron-phonon coupling. Our work establishes a reproducible, transfer-free fabrication route for graphene/perovskite oxide hybrid heterostructures and provides empirical support for the universal growth of graphene on insulating substrates.