Breakdown of Universal Scaling for Nanometer-Sized Bubbles in Graphene

Abstract

We report the formation of nanobubbles on graphene with a radius of the order of 1 nm, using ultralow energy implantation of noble gas ions (He, Ne, Ar) into graphene grown on a Pt(111) surface. We show that the universal scaling of the aspect ratio, which has previously been established for larger bubbles, breaks down when the bubble radius approaches 1 nm, resulting in much larger aspect ratios. Moreover, we observe that the bubble stability and aspect ratio depend on the substrate onto which the graphene is grown (bubbles are stable for Pt but not for Cu) and trapped element. We interpret these dependencies in terms of the atomic compressibility of the noble gas as well as of the adhesion energies between graphene, the substrate, and trapped atoms.

Indentation of graphene nano-bubbles

“…2 It is worth mentioning that the bubbles' radius are sufficiently larger than 1 nm below which we recently have shown that a breakdown in the universal scaling is envisaged. 26 Notice that the aspect ratio values are in quantitative agreement with experiment (see Table 1 † of ref. 26 for the large bubble regime).…”

Electron Dynamics in a Two-Dimensional Nanobubble: A Two-Level System Based on Spatial Density

“…Bubbles in various monolayers and of different dimensions can also be obtained via bottom-up approaches such as ionic irradiations. 24,25 Nanobubbles are able to induce an energy confinement due to the interplay of strain and local screening variations, 15 resulting in a nontrivial circular shape recently observed in experiments. 22,23 Besides being extensively studied via optical response, 10−14,26−28 localized potentials can impact also the transport and associated recombination in different hosting 2D materials 8,29,30 and even lead to excitonic funneling for larger potentials.…”

“…Localized potentials can be either deterministically induced, for example, by patterned substrates − and helium irradiation, or they build up naturally in the form of defects and disorder ,, or nanobubbles. − Bubbles are naturally formed in experiments when depositing the 2D material on a substrate, ,,,− similar to the everyday process of air bubbles forming when putting a plastic foil on glass. Bubbles in various monolayers and of different dimensions can also be obtained via bottom-up approaches such as ionic irradiations. , Nanobubbles are able to induce an energy confinement due to the interplay of strain and local screening variations, resulting in a nontrivial circular shape recently observed in experiments. , Besides being extensively studied via optical response, − ,− localized potentials can impact also the transport and associated recombination in different hosting 2D materials ,, and even lead to excitonic funneling for larger potentials. − …”

Universal shape of graphene nanobubbles on metallic substrate

“…19 Alternatively, a few experimental methods have been designed to gain finer control over bubble formation. These include formation by ions bombarding, 20–24 electrolysis, 25 laser irradiation, 13,26 or by selective adsorption of the substrate. 27 In such experiments, one can tune the size of bubbles by dose or by adsorbate pressure.…”