Formation of wrinkles on graphene induced by nanoparticles: atomic force microscopy study

TL;DR

This study uses atomic force microscopy to analyze how nanoparticle decoration influences wrinkle formation in monolayer graphene, revealing linear relationships between NP density and wrinkle area, and methods to assess graphene morphology and NP detection.

Contribution

It introduces a methodology to determine graphene's contact state, wrinkling patterns, and NP detection from AFM images, linking NP density to wrinkle formation.

Findings

Wrinkle projected area increases linearly with NP density.

AFM can distinguish between contact and delaminated graphene.

NP detection beneath graphene is feasible.

Abstract

Wrinkles in monolayer graphene (GN) affect the GN electronic and transport properties. Defined network of wrinkles can be reached by placing the GN on the substrate decorated with the nanoparticles (NPs). In order to explain mechanism behind the topographically induced changes of the GN electronic structure and to correlate it with the wrinkling, correct description of the GN morphology is of high demand. We demonstrate here how to determine from the atomic force microscopy (AFM) images whether the GN is in the contact with the substrate or it is delaminated, how is the wrinkling of the layer connected with the density of the NPs and if there is the preferential orientation of wrinkles. Also the relevance of detection of the NPs hidden beneath the GN layer is discussed. The study was done on nine samples of the GN on the top of Si-SiO2 substrate, decorated with the metal-oxide NPs of nominal diameter 6 and 10 nm. NP density varied in a range of 20 up to 470 NPs per um2. The projected area of wrinkles was increasing linearly with the increasing NP density, independently on the NP size.