Photoinduced Emission Hopping of Ultrabright and Regularly Occurring Native Quantum Emitters in Aluminum Nitride Grown by Molecular Beam Epitaxy

High Resolution Image Download MS PowerPoint Slide Bright, stable, and reproducible quantum emitters are essential for the development of photon-based quantum information processing. Aluminum nitride (AlN) is an advantageous solid-state system as it possesses a very large bandgap of about 6.1 eV, is technology-relevant, and holds room-temperature quantum emitters among the brightest reported to date. These centers show a broad diversity of spectral emissions and shapes, yet are of still unknown nature and lack reproducibility. Here, we report on regularly occurring (≈0.03 μm –2 ) native single quantum emitters in AlN grown on sapphire by molecular beam epitaxy. The centers emit at a set of wavelengths between 700 and 720 nm with narrow emission lines (4–13 nm), polarized emission, and count rates of up to 2.2 MHz at saturation at room temperature. They are tentatively classified into four types according to their photoluminescence (PL) peak emission. However, they seem to share a common origin. PL spectra at 300 K reveal a complex line shape for some of the centers, which consist of a time-averaged hopping of the zero-phonon line. While most of the centers appear photostable at the time scale of the measurements, we highlight the case of individual emitters subject to a slow photoinduced blinking, which correlates with a discrete change of their emission wavelength. The emission hopping can involve up to five different wavelengths separated by several nanometers each. The investigation of the laser-induced hopping rates against excitation power reveals a complex behavior of saturated absorption or of two-photon process, depending on the excitation wavelength. The origin of the hopping is discussed, likely due to configuration changes of the centers, where Stark shift induced by ionization/recharging of close-by defects can also play a role. Finally, we discuss the center emission range (700–720 mn) and significant occurrence regarding theoretical calculations from Xue et al. ( J. Phys. Chem. Lett. 2020 ), which predict an optical transition of 713.6 nm for the antisite N Al V N center, an intrinsic defect not yet observed experimentally. Our work describes a discrete and large photoinduced emission hopping rarely observed in the solid state and brings new insights into point defects in nitrides.