# Imaging Defective Electronic States in Ultrathin CeO2 Nanostructures Grown on Graphene by Pulsed Laser Deposition

## TL;DR

This paper explores how to grow ultrathin ceria films on graphene and how defects influence their electronic properties.

## Contribution

The study demonstrates defect-controlled growth of CeO2 nanoislands on graphene and reveals ordered oxygen vacancy arrays.

## Key findings

- CeO2 nanoislands preferentially nucleate at graphene defects under pulsed laser deposition.
- Ordered oxygen vacancy arrays are identified on the CeO2 surface using high-resolution STM.
- Electronic interactions between CeO2 and graphene are observed via scanning tunneling spectroscopy.

## Abstract

We report here the growth of ultrathin films of ceria
by pulsed
laser deposition on HOPG/graphene substrates. The controlled growth
of CeO2(111) nanoislands on graphene via pulsed laser deposition
(PLD) demonstrates a strong dependence on the substrate defect density,
where defects serve as preferential nucleation sites. Higher oxygen
partial pressure during deposition enhances surface diffusion, promoting
the formation of triangular dendritic nanostructures. Scanning tunneling
spectroscopy (STS) reveals mutual electronic interactions between
the ceria nanoislands and the graphene substrate, while high-resolution
STM imaging identifies ordered oxygen vacancy arrays within the CeO2 surface. Bias-dependent STM mapping further highlights the
complex electronic configuration of the islands. The presence of these
ordered defects suggests the potential for precise spatial control,
enabling tailored electronic properties through doping or optimized
graphene interactions. These findings advance defect-engineered oxide
nanostructures, offering promising applications in catalysis, sensing,
and optoelectronics via vacancy manipulation in ultrathin films.