Bright UV Single Photon Emission at Point Defects in h-BN

Abstract

To date, quantum sources in the ultraviolet (UV) spectral region have been obtained only in semiconductor quantum dots. Color centers in wide bandgap materials may represent a more effective alternative. However, the quest for UV quantum emitters in bulk crystals faces the difficulty of combining an efficient UV excitation/detection optical setup with the capability of addressing individual color centers in potentially highly defective materials. In this work we overcome this limit by employing an original experimental setup coupling cathodoluminescence within a scanning transmission electron microscope to a Hanbury-Brown-Twiss intensity interferometer. We identify a new extremely bright UV single photon emitter (4.1 eV) in hexagonal boron nitride. Hyperspectral cathodoluminescence maps show a high spatial localization of the emission (∼80 nm) and a typical zero-phonon line plus phonon replica spectroscopic signature, indicating a point defect origin, most likely carbon substitutional at nitrogen sites. An additional nonsingle-photon broad emission may appear in the same spectral region, which can be attributed to intrinsic defects related to electron irradiation.

Defect states in hexagonal boron nitride: Assignments of observed properties and prediction of properties relevant to quantum computation

“…In h-BN, a narrow emission band has been observed with a zero phonon line (ZPL) transition at 1.95 eV [7,48,49] but the origin of this emission is unclear. Based on a broad examination of possible defect sites in h-BN using DFT with the PBE functional, we have reasoned that V N C B forms a likely candidate as its origin [33].…”

Non-linear excitation of quantum emitters in hexagonal boron nitride multiplayers

“…[9][10][11][12] Hexagonal boron nitride (hBN) is another layered material 13,14 that has recently been subject to an increased research due its ability to host room-temperature quantum emitters. [15][16][17] While the origin of these emitters is still under investigation, they exhibit remarkable properties such as ultra-high brightness, full polarization, and tunable emission 18 making them very interesting for quantum sensing and optical communications.…”

Active 2D materials for on-chip nanophotonics and quantum optics

“…Interestingly, experiments report different spectral shape for quantum emitters in hBN with the ZPL energy spanning over a large band, from the UV up to 750 nm [96,103]. Figure 6D shows the spectral distribution of the ZPL emission energy of almost 90 emitters in our experiments.…”