Position-controlled quantum emitters with reproducible emission wavelength in hexagonal boron nitride

Abstract

Single photon emitters (SPEs) in low-dimensional layered materials have recently gained a large interest owing to the auspicious perspectives of integration and extreme miniaturization offered by this class of materials. However, accurate control of both the spatial location and the emission wavelength of the quantum emitters is essentially lacking to date, thus hindering further technological steps towards scalable quantum photonic devices. Here, we evidence SPEs in high purity synthetic hexagonal boron nitride (hBN) that can be activated by an electron beam at chosen locations. SPE ensembles are generated with a spatial accuracy better than the cubed emission wavelength, thus opening the way to integration in optical microstructures. Stable and bright single photon emission is subsequently observed in the visible range up to room temperature upon non-resonant laser excitation. Moreover, the low-temperature emission wavelength is reproducible, with an ensemble distribution of width 3 meV, a statistical dispersion that is more than one order of magnitude lower than the narrowest wavelength spreads obtained in epitaxial hBN samples. Our findings constitute an essential step towards the realization of top-down integrated devices based on identical quantum emitters in 2D materials.

Creating Quantum Emitters in Hexagonal Boron Nitride Deterministically on Chip-Compatible Substrates

“…Figure 3c shows the fitted saturation curve of one of the brightest emitters that saturates at 4.1 mW with a saturation intensity of 1.1 Mcps, comparable to the brightest hBN emitters created by other techniques. 7,13,14,29 SPEs in this work typically exhibit linearly polarized emission (Figure 3c inset), indicating an atomic defect with in-plane dipole moment. 28 The photostability of SPEs is examined by recording their PL time traces when excited by the 532 nm laser at 800 uW.…”

“…A similar strategy was utilized in a recent work to obtain SPEs that are not purely strain-induced in hBN, by growing hBN on dielectric nanopillars using chemical vapor deposition (CVD) 12 . Aside from the above-mentioned methods, gallium focused ion beam (FIB) and electron beam have been demonstrated to create position-controlled SPEs in hBN flakes on a flat substrate 13,14 . However, the fluorescence contamination induced by highenergy gallium ion implantation could be a potential concern in practice, while SPE activation by electron beam suffers from limited spatial precision (> 1 um).…”

“…Our method utilizing an AFM tip is contamination-free, with no additional fluorescent contaminants introduced to hBN, in contrast to radiation-or fabrication-based processes. 8,[12][13][14] By controlling the AFM probe displacement along the vertical direction, lateral indentation sizes ranging from ~150 nm up to 800 nm are achieved with good repeatability. The nano-indentation is followed by argon annealing to fully activate SPEs at the indented sites.…”

Vibrational Properties in Highly Strained Hexagonal Boron Nitride Bubbles

“… 15 hBN is also attracting increasing interest for its intrinsic properties, sustaining the propagation of hyperbolic phonon-polaritons (HPPs) 16 , 17 and hosting single-photon emitters operating at room temperature. 18 − 22 Its remarkable mechanical robustness (breaking strengths of ∼70 GPa and Young’s modulus of ∼800 GPa 4 , 23 , 24 ) was exploited for high-quality mechanical resonators 25 and to reversibly tune the emission wavelength of single-photon emitters via stretching. 26 Strained wrinkles were also found to be ideal candidates for launching HPPs.…”

Donor–Acceptor Pair Quantum Emitters in Hexagonal Boron Nitride

“…The emission spectra of both intrinsic and engineered defects in hBN show broadband spectral range, distinct polarization profiles as well as different quantum efficiencies 9,14,15,17 . Several bottomup growth techniques as well as post-processing approaches such as ion implantation or electron irradiation have been aimed at identifying the sources 12,13,[18][19][20] . In addition, multiple theoretical calculations show that different types of atomic defects may exist, including nitrogen or boron vacancy complexes, antisite defects, or substitutional defects with carbon or oxygen 14,15,17,[21][22][23][24] , but a conclusive evidence for these prediction results is still lacking.…”