Seminarium Fizyki Ciała Stałego

Hexagonal boron nitride (h-BN) has long been used in nanotechnology as an insulating layer in heterostructures with graphene, owing to its wide bandgap (~6 eV). Recently, however, h-BN has gained significant attention due to the discovery of various color centers in its samples that exhibit single-photon emission. These single-photon emitters in h-BN are particularly attractive due to their excellent brightness and photostability, even at room temperature. Additionally, the wide bandgap of h-BN enables the hosting of single-photon emitters across a broad spectral range, from the infrared to the ultraviolet.While experiments suggest a correlation between the intensity of emission from many of these centers and the carbon content in h-BN samples, the chemical nature of most of the observed emitters remains unclear. To further advance the field, it is crucial to identify the point defects responsible for the observed emissions. First-principles calculations could play a pivotal role in achieving this goal.In my presentation I will discuss results of first-principles calculations focused on identifying three groups of emitters in h-BN, most likely associated with carbon defects: (i) ultraviolet emitters (ZPL 4.1 eV), (ii) so called “visible emitters” (ZPL between 1.6 and 2.1 eV), and (iii) blue emitters (ZPL 2.85 eV).