Single-Photon Source Monolithically Integrated on a 300 mm Silicon Wafer Using III–V Nano-ridge Engineering

Single-photon sources (SPSs) are essential for the development of practical quantum technologies, and their integration with silicon photonics is considered the preferred route for scalable implementations. To fully leverage the mature fabrication processes of CMOS foundries, we investigated the use of nano-ridge engineering (NRE) for the monolithic integration of InAs quantum dot (QD)-based SPSs on 300 mm Si wafers. These nano-ridges are made of high-crystal-quality GaAs selectively grown on a trench-patterned wafer, forming waveguides coplanar to the Si chip. The InAs QDs are embedded in these waveguides to form SPSs. In this work, a new device concept and integration approach is presented, showing that beta factors as high as 0.87 can be achieved owing to the high refractive index contrast between GaAs and SiO₂. Then, a first proof of concept is demonstrated. Selective deposition of QDs on top of a diamond-shaped nano-ridge is used to center the dots within the final box-shaped nano-ridge, overgrown after the QD deposition, and to reduce the overall QD density per ridge. The grown QDs showed good spectral properties with line widths as low as 32.7 μeV at 955 nm. The autocorrelation measurements from a selected QD underlines the single-photon nature of the grown structure, with a g²(0) = 0.091 ± 0.005 under nonresonant pulsed excitation. These findings establish a solid foundation for future advancements, including implementing a PIN junction to enhance indistinguishability and extending the emission wavelength to the telecommunication O-band via the growth on InGaAs nano-ridges.