A Simple Method of Growth and Transfer of Bilayer Graphene / Few-Layer Boron Nitride Suspended Heterostructures onto Large 200 µm Etched in Silicon "Trenches".*

Two-dimensional heterostructures remain at the forefront of contemporary research. Bilayer graphene (BLGr) and few-layer boron nitride (FLBN) have been studied extensively for their unique electronic and mechanical properties and facile synthesis. Their similar hexagonal crystal structures allow for optimal stacking. Adding more layers has been shown to alter material properties. While others have suspended 2D heterostructures, membranes are often ruptured due to surface tension, limiting their size and yield. In this study, we demonstrate the fabrication of heterostructures using chemical vapor deposition (CVD) grown BLGr and FLBN and a direct transfer method to create suspended stacks. BLGr was transferred directly onto FLBN substrate while overlayed with polymethyl methacrylate (PMMA), and the entire stack was then transferred onto 200 µm wide trenches. Noteworthy is the use of polydimethylsiloxane (PDMS) block assistance to prevent stress-induced rupture during the transfer process, which was very effective. Raman spectroscopy and scanning electron microscopy (SEM) were used to study quality and integrity of the resulting suspended heterostructure. To the best of our knowledge, this is the first demonstration of large-scale suspended heterostructures reported to date.