Fig. 1. AFM-assisted experimental set-up and cohesion energy measurements.

a Schematic of the AFM set-up used to perform interfacial adhesion measurements under different annealing temperatures. Left inset: SEM image of the microheater with an MoS₂ flake exfoliated on the heating line whose corresponding AFM image was taken by the G crystal tip. Right Inset: SEM images of the tip-attached G circular nanomesa (top image) and hBN square nanomesa (bottom image). Scale bars indicate 100 nm. b Typical retraction F–d curves recorded at the intact homointerface of G (in red), hBN (in blue), and MoS₂ (in brown) crystals and also the approach F–d curve (in gray) recorded at the hBN tip/substrate homointerface. The light blue-shaded area under the retraction curve at the hBN homointerface represents the cohesion energy in units of Joules. Each raw data set was given an offset to provide the same equilibrium position for all F–d curves. Top panel: SEM images of lower section of the nanomesas on their corresponding bulk substrate after the full tip retraction. Perspective AFM image corresponding to the SEM image of the MoS₂ nanomesa is also shown. Scale bars indicate 50 nm. c Typical shear force–lateral piezo displacement curves recorded at the intact homointerface of G (in red), hBN (in blue), and MoS₂ (in brown) crystals. Schematic inset shows that the 2D crystal substrate moves along the long axis of the cantilever tip at zero contact force. Top panel: Corresponding SEM images of the sheared G, hBN, and MoS₂ nanomesas. Scale bars indicate 50 nm. d Typical retraction F–d curves recorded at the interface of tip-attached G nanomesa/G substrate (in blue), bare Si tip-attached water nanomeniscus/SiO_x substrate (in blue), and tip-attached G mesa/Cu substrate (in brown) at the relative humidity of 15, 70, and 15%, respectively. Schematic inset shows the meniscus rupture between the in situ flattened Si tip and the SiO_x/Si substrate, where the energy required to rupture the nanomeniscus is roughly obtained by dividing the area under the F–d curve over the area of the flat tip. e Cohesion energy of G, hBN, and MoS₂ crystals obtained by normal force measurements (squares with cyan borders) and shear force measurements (circles with orange borders) at room temperature. Data are presented as average ± standard deviation.