  Fabrication of custom-built heterostructures based on stacked 2D materials
provides an effective method to controllably tune electronic and optical
properties. To that end, optimizing fabrication techniques for building these
heterostructures is imperative. A common challenge in layer-by-layer assembly
of 2D materials is the formation of bubbles at the atomically thin interfaces.
We propose a technique for addressing this issue by removing the bubbles formed
at the heterostructure interface in a custom-defined area using the heat
generated by a laser, equipped with raster scanning capabilities. We
demonstrate that the density of bubbles formed at graphene-ReS2 interfaces can
be controllably reduced using this method. We discuss an understanding of the
flattening mechanism by considering the interplay of interface thermal
conductivities and adhesion energies between two atomically thin 2D materials.
