Evolution of carbon color centers in pristine hexagonal boron nitride by electric field

Seungmin Park
Kyung Hee University, Seoul, Republic of Korea _______________________________________

Hexagonal boron nitride (hBN) is a unique two-dimensional van der Waals material with a wide bandgap of 6.2 eV, optical transparency, and stability under ambient conditions and high temperatures. Due to its wide bandgap, color centers at various wavelengths can be created within hBN, which have been studied as quantum emitters. Carbon color centers in hBN exhibit an emission at 4.09 eV in the ultraviolet (UV) range, which has been confirmed via UV photoluminescence (PL) and cathodoluminescence (CL). In this work, we applied an electric field to hBN using graphene electrodes to create carbon color centers. Initially, when the electric field was applied, the current through pristine hBN exhibited direct tunneling, and electroluminescence (EL) from pristine hBN showed visible emission. After increasing the electric field, the tunneling mechanism transition occurred direct tunneling to Fowler-Nordheim tunneling, and the EL spectrum shifted to an emission at 4.09 eV. Concurrently with this tunneling transition, the EL spectrum displayed sharp peaks in the UV region, which closely matched the simulated data for evolving carbon color centers.

Email: octo_r3500@khu.ac.kr