Large-Scale, High-Yield Laser Fabrication of Bright and Pure Single-Photon Emitters at Room Temperature in Hexagonal Boron Nitride

Abstract

Single-photon emitters (SPEs) play an important role in many optical quantum technologies. However, an efficient large-scale approach to the generation of high-quality SPE arrays remains an elusive goal at room temperature. Here, we demonstrate a scalable method of generating SPE arrays in hexagonal boron nitride (hBN) with high yield, brightness, and purity using single-pulse irradiation by a femtosecond laser. Our use of a single pulse per defect pattern minimized heat-related damages and improved the purity of SPEs compared with the previous laser-based approaches. Under the optimized fabrication and post-treatment conditions, SPE arrays were successfully generated from the 3.0 μm defect patterns with 43% yield, the highest among the 2D-based top-down approaches. Importantly, we found that 100% of the bright defect patterns are SPEs with g 2(0) < 0.5 under such conditions, with the lowest g 2(0) = 0.06 ± 0.03. Our SPEs also exhibit the highest brightness with the saturation SPE rate at 7.15 million counts per second. We believe that our overall high-quality and large-scale approach will help a wide range of applications of SPEs in on-chip quantum technologies.

Quantum Emitters in Hexagonal Boron Nitride

“…Xu et al produced SPE arrays by nano-indentationan AFM tip was used to fabricate arrays of holes in hBN (Figure c) . Ultrashort laser pulses (Figure d) have been used to fabricate visible SPEs ,− and ensembles of V B – centers, as have focused ion beams (Figure e,f). − The image in Figure e shows four 7×7 spot arrays fabricated in a flake of hBN by a Ga + beam . Here, the ion dose was high and ion beam sputtering produced a hole at each irradiation site.…”

“…All the methods are stochastic by their nature. Most attempts at generating SPE arrays have success rates below 50%, ,,, though a number of works report arrays in which a high majority (≳80%) of sites are SPEs. , Also, most of the methods generate unwanted crystal damage as a byproduct. This is illustrated dramatically by the laser ablation crater in Figure d, and by holes produced by nano-indentation and ion beam sputtering (Figure c,e).…”

“…24 (d) Material breakdown using ultrashort laser pulses. 25 The image is an overlay of AFM and PL maps showing a PL emission at a crater generated by a single laser pulse (scale bar = 2 μm). beam sputtering produced a hole at each irradiation site.…”

“…All the methods are stochastic by their nature. Most attempts at generating SPE arrays have success rates below 50%, 13,24,25,31 though a number of works report arrays in which a high majority (≳80%) of sites are SPEs. 23,32 Also, most of the methods generate unwanted crystal damage as a byproduct.…”

“…(c) Nano-indentation using an AFM tip 24. (d) Material breakdown using ultrashort laser pulses 25. The image is an overlay of AFM and PL maps showing a PL emission at a crater generated by a single laser pulse (scale bar = 2 μm).…”