Synthesis of 2D materials by direct heating of bulk sources

Synthesis of high-quality 2D materials usually requires reactors/furnaces of various levels of complexities. A simple method of growing 2D materials or their combined structures (heterostructure, alloys etc.) that is easy to set up and run can accelerate 2D research. We find that single and multilayered 2D materials of various types can be easily fabricated by direct thermal evaporation. This is in stark contrast with conventional vapor-phase techniques that require chemical reactions of precursors and flow of an inert carrier gas so, substantially reducing the cost and complexities. Sources of target nanomaterials are taken in commercial bulk form, reduced to powder, placed on a clean container in close proximity of target substrate in an inert atmosphere, then heated to and held at a range of material-specific high temperatures and durations. The nanomaterials evaporate and deposit directly on the substrate in the form of well-formed crystals. The synthesis methodology is much simpler than the other methods (CVD, MBE, etc.). We present detailed analysis (AFM, optical images, Raman, photoluminescence) of various types of 2D materials/structures possible via direct, mixed, and sequential evaporation of bulk powders.