Room-Temperature Quantum Emitter in Aluminum Nitride

Abstract

A device that is able to produce single photons is a fundamental building block for a number of quantum technologies. Significant progress has been made in engineering quantum emission in the solid state, for instance, using semiconductor quantum dots as well as defect sites in bulk and two-dimensional materials. Here we report the discovery of a room-temperature quantum emitter embedded deep within the band gap of aluminum nitride. Using spectral, polarization, and photon-counting time-resolved measurements we demonstrate bright (>10⁵ counts s^-1), pure (g ⁽²⁾(0) < 0.2), and polarized room-temperature quantum light emission from color centers in this commercially important semiconductor.

Figure 1

Confocal mapping of point-like emitters in AlN. (a) Crystal structure of aluminum nitride. The polar crystal axis [0001] is indicated. (b) Optical image of the sample with titanium markers. (c) Intensity scan map of the sample. The three emitters, C1–C3, studied in this work are labeled.

Figure 2

Room-temperature spectroscopy of color centers in AlN. (a) Spectral and autocorrelation measurements of the three emitters, labeled C1, C2, and C3 in the intensity scan map in Figure 1c. (b) Histogram showing the energy in which the spectra for 20 emitters has fallen to half its maximum intensity, on the high energy side. The orange data represents emitters where an obvious zero phonon line cannot be identified. The spectrum for C1 is overlaid, with phonon-shifted energies of the zero phonon line labeled. (c) Raman spectrum showing phonon modes in the AlN on sapphire substrate.

Figure 3

Photostability, autocorrelation, polarization, and power dependence of C1 at room temperature. (a) Confocal scan over the emitter, with an accompanying X and Y slice. (b) Power-dependent measurement of intensity showing saturation of intensity at high pump laser power. (c) Autocorrelation measurement at a pump power of 30 μW (orange), 350 μW (blue), and 3.2 mW (purple), demonstrating both room-temperature antibunching and bunching. (d) Time-resolved stability measurement. (e) Polarization measurement in both excitation and collection. (f) Illustration of the three energy level model used to fit the data in (c).

Figure 4

Temperature dependence, spectral, and autocorrelation measurements of C1 at low temperature. (a) Photoluminescence spectrum of C1 at 4 K. (b) Temperature dependence of the zero phonon line energy and full width half-maximum between 4 and 300 K. (c) Autocorrelation measurement at 4 K under 532 nm excitation at 4 mW.