Room-temperature single photon emitters in cubic boron nitride nanocrystals

Abstract

Color centers in wide bandgap semiconductors are attracting broad attention as platforms for quantum technologies relying on room-temperature single-photon emission (SPE), and for nanoscale metrology applications building on the centers' response to electric and magnetic fields. Here, we demonstrate room-temperature SPE from defects in cubic boron nitride (cBN) nanocrystals, which we unambiguously assign to the cubic phase using spectrally resolved Raman imaging. These isolated spots show photoluminescence (PL) spectra with zero-phonon lines (ZPLs) within the visible region (496-700 nm) when subject to sub-bandgap laser excitation. Second-order autocorrelation of the emitted photons reveals antibunching with ɡ 2 (0) ~ 0.2, and a decay constant of 2.75 ns that is further confirmed through fluorescence lifetime measurements. The results presented herein prove the existence of optically addressable isolated quantum emitters originating from defects in cBN, making this material an interesting platform for opto-electronic devices and quantum applications.With an atomic structure equivalent to that of diamond, refractive index close to 2.1, an optical bandgap exceeding 10 eV, and the possibility of n-and p-type doping, cubic boron nitride (cBN) is attracting interest as a host for atomic defects with optical features across a wide region of the electromagnetic spectrum. 1-3 A combination of photoluminescence (PL) and electron paramagnetic resonance (EPR) studies have shed light on the optical and electronic properties of a range of point defects, from vacancies to heavy-metals and rare-earth elements. 4-9

Enhanced Emission from Defect Levels in Multilayer MoS2

“…[ 16 ] The sensitive characterization of defects can help understand mechanisms of other defect emission processes, such as single photon emission in transition metal dichalcogenides (TMDs) [ 17 ] and hexagonal boron nitride (hBN). [ 18 ] Recent realizations of defect‐based stimulated emission in other technologically prominent crystals include nitrogen vacancy centers in diamond, [ 19 ] and rare‐earth dopants in Si nanocrystal sensitizers. [ 20,21 ] However, despite the realization of excitonic lasers based on free excitons in monolayer dichalcogenides, [ 22,23 ] stimulated emission from defects in layered materials has not been achieved so far.…”

Microstructure and Conduction Electron Quantum Properties of Small Diamond Cubic α-Sn Nanocrystals Embedded in Cubic Boron Nitride Crystals

“…Based on the successful fitting of the experimental temperature dependence of the ΔB 1 linewidth (Figure 9) and line amplitude A 1 (Figure 8a) with eqs 8 and 9 , respectively, one obtains an excellent fit of the temperature dependence for the integrated intensity I 1 of the Sn1 line (Figure 8b) with the formula: (11) Here, we used the same notations as those employed in eqs 8 and 9, excepting the energy separations between the magnetic S = 1/2 doublet level responsible for the Sn1 line and the neighboring lower and upper levels, replaced here by the Δ QC average separation. The fitting parameters given in Table 4 (line 3) exhibit values close to those obtained from the separate fitting of the temperature dependences of ΔB 1 (Table 4, line 1) and amplitude A 1 (Table 4, line 2), which confirms the validity of the above analysis.…”

“…Cubic boron nitride (cBN) with zinc blende structure is a wide band-gap (∼6.4 eV) semiconductor, industrially prepared as a crystalline superhard powder by the temperature gradient method, at high pressure and high temperature (HP-HT), in a variety of alkali or alkali-earth B-N solvents to which additives and/or catalysts are added. − Despite the cBN outstanding properties, − the presence, distribution, and atomic properties of the impurities incorporated in its crystal lattice are little known. The main reason is the extreme difficulty of preparing enough large (mm-sized), good quality single crystals with controlled impurity content, as required for physical investigations. − With recent advances in microanalysis and microstructural techniques using electron beams, , it is now possible to investigate the presence, nature, and aggregation state of the impurities incorporated in the submillimeter-sized cBN crystallites found in large-sized commercial superabrasive powders. Thus, recent studies by analytical high-resolution scanning transmission electron microscopy/transmission electron microscopy [a-(HR)­STEM/TEM], cathodoluminescence, ionoluminescence, and electron spin resonance (ESR) evidenced the presence and non-uniform distribution of certain impurities incorporated in the cBN crystallites. − As reported here, tin (Sn) is such an impurity, which we found in dark BORAZON CBN Type 1 crystallites.…”

“…The main reason is the extreme difficulty of preparing enough large (mm-sized), good quality single crystals with controlled impurity content, as required for physical investigations. 8 − 11 With recent advances in microanalysis and microstructural techniques using electron beams, 12 , 13 it is now possible to investigate the presence, nature, and aggregation state of the impurities incorporated in the submillimeter-sized cBN crystallites found in large-sized commercial superabrasive powders. Thus, recent studies by analytical high-resolution scanning transmission electron microscopy/transmission electron microscopy [a-(HR)STEM/TEM], cathodoluminescence, ionoluminescence, and electron spin resonance (ESR) evidenced the presence and non-uniform distribution of certain impurities incorporated in the cBN crystallites.…”