Quasi‐2D Crystalline γ‐Alumina Grown by Graphene‐Assisted Atomic Layer Deposition

Abstract

AbstractThis study presents a facile high‐yield bottom‐up fabrication and morphology‐structure investigations of a free‐standing network of multi‐layer quasi‐2D flakes consisting of intrinsically nonlayered γ‐Al2O3. The synthesis comprises a multi‐cycle atomic layer deposition (ALD) of amorphous alumina that uses an interconnected graphene network as a growth scaffold followed by ≈800 °C air anneal. The structures are studied by X‐ray diffraction, selected area electron diffraction, and high‐resolution transmission electron microscopy, while electric properties are assessed with the help of two‐terminal dc‐transport measurements. The individual flakes comprise nanocrystalline phase cubic spinel γ‐Al2O3 with a close‐packed cubic texture in the 〈111〉cubic ALD‐induced growth direction. The charge transport is confirmed to be Ohmic with the room temperature electrical conductivity approaching ≈10−8 S m−1. This work opens a door to a low‐cost highly scalable synthesis of a variety of quasi‐2D metal oxides for widespread uses ranging from support material, sensing to environmental remediation.