Color Centers in Hexagonal Boron Nitride Nanosheet-Based Heterojunctions: Implications for Quantum Emitters and Ultrathin Sensors

Luminescence defects, which are commonly known as color centers in hexagonal boron nitride (hBN), are promising for applications in quantum sensing and emitters, but most of them are challenging to efficiently fabricate and identify. Here, we explore the photoluminescence (PL) spectra of color centers in hBN-based heterojunctions. We clearly observed a series of PL spectra with peaks at ∼680 nm in monolayer and nanometer-thick hBN/SiO2 heterojunctions after helium-ion irradiation; the line shape and line width of those PL spectra are the same as the boron vacancy in bulk hBN with a peak at 818 nm. We also demonstrated a generation strategy for a carbon-related color center with a zero phonon line at 580.7 nm in a graphene/hBN/SiO2 heterojunction using 1 keV argon-ion implantation without subsequent annealing. Furthermore, density functional theory calculations were used to speculate on the atomic structures and substrate effects of color centers in hBN-based heterojunctions. This work provides a highly efficient fabrication method for carbon-related color centers in monolayer hBN as quantum emitters and finds that the color centers with peaks at ∼680 nm in monolayer hBN are useful for the monitoring of the ion beam