Polymer-Free Transfer of 2D Materials onto III-V Semiconductor Surfaces for Scanning Probe Microscopy and Molecule-Encapsulation Experiments

A tabletop dry touch-transfer method that employs van der Waals forces was used to transfer multi to few-layer flakes of hexagonal boron nitride (hBN) and graphite onto cleaved, atomically flat GaAs (110) and InSb (110) surfaces. This method offers a cleaner alternative to current polymer-involved transfer methods, which leave polymer traces on the sample surface and require an extensive cleaning process for scanning probe microscopy (SPM) study.
An attractive application of this touch-transfer method is the encapsulation of target molecules between the semiconductor surface and graphene flakes for scanning tunneling microscopy (STM) studies. The conductivity of graphene allows us to probe the electronic states of otherwise challenging molecules and explore their possible applications. We present results of encapsulation of deionized water droplets between GaAs (110) and thinned graphite, characterized by atomic force (AFM), scanning electron (SEM) and optical microscopy techniques. Further studies will utilize nano-squeegeeing techniques using contact-mode AFM to control the placement of trapped water molecules.