Spatially-resolved UV-C emission in epitaxial monolayer boron nitride

Abstract

We report hyperspectral imaging in the UV-C spectral domain in epitaxial monolayers of hexagonal boron nitride (hBN). Under quasi-resonant laser excitation, the UV-C emission of monolayer hBN consists in resonant Raman scattering and photoluminescence, which appear to be spatially uncorrelated. Systematic measurements as a function of the excitation energy bring evidence of a photoluminescence singlet at ~6.045 eV. The spatial variations of the photoluminescence energy are found to be around ~10 meV, revealing that the inhomogeneous broadening is lower than the average photoluminescence linewidth of ~25 meV, a value close to the radiative limit in monolayer hBN. Our methodology provides an accurate framework for assessing the opto-electronic properties of hBN in the prospect of scalable hBN-based devices fabricated by epitaxy.