The role of ambient ice-like water adlayers formed at the interfaces of graphene on hydrophobic and hydrophilic substrates probed using scanning probe microscopy

Abstract

In this work, we report the role of ice-like water adlayers (IWLs) formed under ambient conditions in between mechanically exfoliated as-prepared and patterned few layer graphene (FLG) and multi-layer graphene (MLG) on hydrophobic Si and hydrophilic SiO2/Si substrates. The growth of the IWL is probed by measuring the height changes in graphene using intermittent contact atomic force microscopy (IC-AFM) and their electrostatic effect is studied using electrostatic force microscopy (EFM) over time. It is found that more IWLs are formed within a shorter period of time, when both as-prepared graphene and underlying substrates are either hydrophobic or hydrophilic in nature. In contrast, AFM voltage nanolithographically patterned trenches on FLG and MLG on the Si substrate show quick formation of IWLs. The effect of IWL formed, on the dimensions of trenches, is correlated with the variation of the measured EFM phase shift over time. This study demonstrates the dependence of the formation of IWLs under ambient conditions on the affinity towards water, at the interface of graphene on hydrophobic and hydrophilic substrates, which has important implications for the performance of graphene-based nanoelectronic devices.

Mechanics of spontaneously formed nanoblisters trapped by transferred 2D crystals

“…Our model can hence predict an upper limit for the adhesion energy of these 2D material interfaces as Γ ≤ γ w ðcos θ m + cos θ s Þ (noted as the yellow region in Table 1). This simple relation also quantitatively offers a criterion for the interesting observation of room-temperature ice formation in a 2D nanochannel (50)(51)(52)(53)(54)(55)(56). This formula can also help explain the so-called self-cleaning mechanism (formation of blisters) which is typically observed at atomically smooth, hydrophobic 2D heterostructure interfaces such as graphene-V 2 O 5 (9).…”

Water confined in two-dimensions: Fundamentals and applications

“…Electrostatic force microscopy (EFM) has been deployed to study the influence of intercalated water on the 2D material cover [290][291][292][293]. For increasing graphene thickness, the influence of the adsorbed water is screened more effectively [291,293]. EFM measurements of multilayer graphene reveal an increase of the phase shift towards the bulk constant [293,294].…”

“…For increasing graphene thickness, the influence of the adsorbed water is screened more effectively [291,293]. EFM measurements of multilayer graphene reveal an increase of the phase shift towards the bulk constant [293,294].…”

A contactless single-step process for simultaneous nanoscale patterning and cleaning of large-area graphene

“…These are coated directly onto the graphene membrane. Examples of pattern-defining layers include selfassembly of polystyrene nanosphere [1,2], block copolymers [32,33], nanoimprinting [34,35], atomic force microscopy (AFM) based nanolithography [36,37], porous anodic alumina [15], electron beam lithography (EBL) [38], and extreme UV lithography [39]. The downsides of using coating layers are, at first, the fact that the approach introduces a significant amount of contamination which is difficult to be subsequently removed completely [40,41], and second, the damage to the self-supporting membranes due to the chemical and the mechanical forces involved.…”