2D materials for infrared sensing and hyperspectral imaging

2D materials for sensing applications offer several advantages—high absorption in thin layers, the lack of surface dangling bonds or major defects, ease of materials synthesis and device fabrication, and relaxed substrate lattice-matching requirements. We theoretically explore two 2D materials, hexagonal boron phosphide and hexagonal boron arsenide, for possible infrared sensing and hyperspectral applications. Using first principles, we calculate the total energy of formation, band structures, and absorption coefficient of monolayer and bilayer materials. We evaluate the bandgap and absorption coefficient of bilayers as a function of layer stacking, number of layers, and applied field across the layers. We find that with a choice of stacking order, number of layers, and applied field, the material can be chosen appropriately for sensing of short-, mid-, or long-wavelength infrared radiation. Furthermore, the absorption is increased in these materials with applied electric fields. With the ability to dynamically change the bandgap with an external electric field, this class of materials is ideally suited for continuous hyperspectral sensing in the infrared.