Electron irradiation as a method for controlling luminescence of hexagonal boron nitride
Hexagonal boron nitride (hBN) is characterized by two main point defect-related luminescence bands with the peaks in visible, at 650 nm (1.9 eV), and UV, 320 nm (4 eV) spectral regions, which possess the properties of single photon emitters (SPE). We demonstrate that sufficiently long irradiation of thin hBN flakes in a scanning electron microscope with electron beam with energies from 5 keV to 20 keV and the flux equal or more than 1015 cm–2s–1 resulted in a drastic increase in the integral intensity of the 4 eV band previously associated with carbon-related defects. The effect of the irradiation induced luminescence enhancement increases with the decrease of the electron beam energy that corresponds well with the calculated energy losses in thin samples. An increase in the concentration of carbon-related defects introduced into the sample from surface carbon contaminated layer via recombination-enhanced migration or changes of the charge state of existing defects could be supposed to be mechanisms of the observed effect. The obtained results demonstrate the possibility of local control of UV SPE concentration in hBN.