Extrinsic Effects on the Optical Properties of Surface Color Defects Generated in Hexagonal Boron Nitride Nanosheets

Abstract

Hexagonal boron nitride (hBN) is a wide-band gap van der Waals material able to host light-emitting centers behaving as single photon sources. Here, we report the generation of color defects in hBN nanosheets dispersed on different kinds of substrates by thermal treatment processes. The optical properties of these defects have been studied using microspectroscopy techniques and far-field simulations of their light emission. Using these techniques, we have found that subsequent ozone treatments of the deposited hBN nanosheets improve the optical emission properties of created defects, as revealed by their zero-phonon linewidth narrowing and reduction of background emission. Microlocalized color defects deposited on dielectric substrates show bright (≈1 MHz) and stable room-temperature light emission with zero-phonon line peak energy varying from 1.56 to 2.27 eV, being the most probable value 2.16 eV. In addition to this, we have observed a substrate dependence of the optical performance of the generated color defects. The energy range of the emitters prepared on gold substrates is strongly reduced, as compared to that observed in dielectric substrates or even alumina. We attribute this effect to the quenching of low-energy color defects (these of energies lower than 1.9 eV) when gold substrates are used, which reveals the surface nature of the defects created in hBN nanosheets. Results described here are important for future quantum light experiments and their integration in photonic chips.

Towards Integration of Two-Dimensional Hexagonal Boron Nitride (2D h-BN) in Energy Conversion and Storage Devices

“…This could be done either by inducing reactions between B-and N-rich precursor materials to generate h-BN flakes (bottom-up) or breaking the h-BN layered structure apart to form nano-or micro-sized flakes (top-down) [31]. The former methods are often employed to produce atomically thin 2D h-BN or when surface charge uniformity is important (i.e., photonics or solar cells) [32]. For instance, chemical vapor deposition (CVD) has shown to be a promising technique to produce homogeneous large area h-BN layers.…”

Microstructure Engineering of Hexagonal Boron Nitride for Single‐Photon Emitter Applications

“…c) Reproduced with permission. [ 18 ] Copyright 2021, The Authors. Published by American Chemical Society.…”

“…Furthermore, Krečmarová et al. [ 18 ] summarized a histogram of the zero phonon line (ZPL) energy corresponding to point defects, as shown in Figure 2c. Among various luminous point defects, V N , V N N B , and V N C B were found to be more suitable for SPE.…”

“…Gao et al [17] investigated the radiative lifetime and energy of candidate defect SPE in h-BN using calculations (Figure 2b). Furthermore, Krečmarová et al [18] summarized a histogram of the zero phonon line (ZPL) energy corresponding to point defects, as shown in Figure 2c. Among various luminous point defects, V N , V N N B , and V N C B were found to be more suitable for SPE.…”

“…Copyright 2021, The Authors, published by Springer Nature. c) Reproduced with permission [18]. Copyright 2021, The Authors.…”