Strongly Coherent Single-Photon Emission from Site-Controlled InGaN Quantum Dots Embedded in GaN Nanopyramids

Abstract

Group III-nitride materials have drawn a great deal of renewed interest due to their versatile characteristics as quantum emitters including room-temperature operation, widely tunable wavelengths from ultraviolet to infrared, and a high degree of linear polarization. However, most reported results for III-nitride-based quantum emitters show large inhomogeneous line width broadening in comparison to their lifetime-limited values, which is detrimental to achieving indistinguishability with high visibility. To overcome this, we propose an unprecedented InGaN quantum dot formation technique at the apex of GaN nanopyramid structures, which significantly suppresses inhomogeneous line width broadening. Using high-resolution transmission electron microscopy, a site-controlled InGaN quantum dot with small height (<2 nm) was estimated. No measurable screening effect or frequency jitter of the single-photon emission was observed, which leads to the narrow homogeneous emission line width (64 ± 8 μeV) beyond the spectral resolution limit via Fourier-transform spectroscopy. The emitted photons exhibited superb antibunching characteristics with a near-unity degree of linear polarization, which is highly relevant for polarized nonclassical light sources for applications in quantum information processing.

III–V compounds as single photon emitters

“…The crystallographic and electronic structure and origin of the hBN defect is still under debate. Much more effort is required to improve the growth of III-nitrides and 2D materials, particularly in attempts to control identical QDs and spectrally stable defects [140]. High temperature SPEs are of significant importance for practical operations [141].…”

Nanoscale Focus Pinspot for High-Purity Quantum Emitters via Focused-Ion-Beam-Induced Luminescence Quenching

“…47 However, at elevating temperature, broadening of the QD emission occurs due to the phonon interaction, and consequent decrease in the QD peak intensity degrades the SNR at the peak emission energy, reducing the single-photon purity. 46,47 Thus, elimination of QW and other background emission becomes more important for achieving the high-temperature operation of the single-photon emission.…”

Single‐photon emission from a further confined InGaN/GaN quantum disc via reverse‐reaction growth

“…We note that the value of g (2) (0) we present here is comparable with the most pure single-photon emission reported to date from the InGaN/GaN material system of various nanostructure geometries. 21,46 The residual nonzero g (2) (0) value is due to the unfiltered spectral background contamination that enters the HBT setup during the measurement. Analysis of the background level in Figure 3A allows us to estimate a background-corrected g (2) (0) value of approximately 0.05, essentially zero to within the experimental error, 47 indicating that the QD itself is a very pure single-photon emitter (although we note that it is the measured value of 0.11 that truly represents the degree to which the QD/nanowire system is able to provide single photons).…”

“…Through exploiting these advantages, optically and electrically driven single-photon emission in InGaN QDs has been reported using various substrates, fabrication techniques, and nanostructure geometries. These have included InGaN QDs in self-assembled Al(Ga)N (aluminum gallium nitride) nanowires, 18,19 InGaN QDs at the apices of site-controlled GaN (gallium nitride) pyramids, 20,21 InGaN/GaN self-organized QDs, 22,23 m-plane InGaN QDs on GaN nanowires, 24 and site-controlled InGaN/GaN QDs defined via etching of planar single quantum wells. 25,26 It is anticipated that by using self-assembled structures to localize the QDs, a cleaner environment can be achieved, which will result in narrower emission linewidths due to a suppression of typically observed spectral diffusion effects.…”