Defect engineering of hexagonal boron nitride nanosheets via hydrogen plasma irradiation

Atomic defects capable of hosting optically active centers in hexagonal boron nitride (h-BN) demonstrate a rich spin and optoelectronic physics that can be exploited for next-generation nanoelectronics and photonics. The precise controlling of these active defects is thus of particular importance. Here, we demonstrate the modulation of optoelectronic properties of atomically thin h-BN nanosheets (BNNSs) based on defect engineering via hydrogen plasma irradiation. Detailed studies resolve the generation of point defects and oxygen related defects uniformly in h-BN lattice after treated by hydrogen plasma. These tailored defects can lead to stable room-temperature luminescent emissions varying from 440 nm (ca. 2.8 eV) to 580 nm (ca. 2.1 eV) in BNNSs and multiple recombination channels. In addition, we show significant variations in both lattice structure and energy bandgap in BNNSs that can be tuned by the hydrogen plasma treatment. Density functional theory calculations verify the nature of the defect-induced optoelectronic behavior. These results are highly valuable for the fabrication of future two-dimensional semiconducting electronics, optoelectronics, and spintronics.