Room Temperature Quantum Emitters in Aluminum Nitride Epilayers on Silicon

Aluminum nitride (AlN) is a compound semiconductor with a wide band-gap, boasting well-established fabrication processes with a transparency window ranging from ultraviolet to mid-infrared. Additionally, AlN possesses both χ (2) and χ (3) non-linearity allowing for processes such as spontaneous parametric down conversion [1] and spontaneous four wave mixing to occur. Devices such as low-loss waveguides and ring resonators in AlN have been reported demonstrating Q-factors exceeding 106 [2] making AlN a promising platform for quantum photonic technologies. Recently, AlN on sapphire has been shown to host quantum emitters (QEs) which emit quantum light at room-temperature [3]. The well known chromium related background fluorescence from sapphire [4] substrates reduces the single photon purity, as well as its unsuitability for scalable processing makes it desirable to identify QEs compatible with other material platforms. In addition, silicon substrates present a wide array of advantages for integrating quantum light sources into electrical devices. The ubiquitous adoption of silicon by industry means there are mature processing techniques with the potential to access CMOS compatible cleanrooms.

We will present the first report of QEs in a III-nitride material on a silicon substrate [5]. We study two samples grown by plasma vapour deposition of nano-columns (PVDNC) and metal organic vapour phase epitaxy (MOVPE) on silicon [111] substrates. Both samples contain QEs with a low enough density to be individually addressed. The emission spectra of these QEs is reminiscent of QEs in AlN on sapphire with a low Debye-Waller factor spectrum centered around ≈800 nm. The emission from the QEs is linearly polarized with orthogonally oriented absorption and emission dipoles. The quantum nature of the emission was validated with a Hanbury-Brown and Twiss interferometer in both continuous wave and pulsed mode measurements giving a value of g (2)(0) = 0.41±0.03 for the pulsed measurement. We measure few-nanosecond excited state lifetimes are found which is consistent with other room-temperature quantum emitters in IIInitrides. The discovery of a room-temperature quantum light source in AlN on silicon presents opportunities for commercial, off the shelf single-photon sources.

References
1 - Guo et al 2016, Light Sci Appl, (6) e16259
2 - Li et al 2021, Nanophotonics 10 (9) 2346-2387
3 - Bishop et al 2020, ACS Photonics 2020 7 (7), 1636-1641
4 - Kusuma et al, 2018, J. Phys.: Conf. Ser. (1170) 012054
5 - Cannon et al 2023, Appl. Phys. Lett. 2024 (124), 244001