Adding quantum dots to microdisks makes silicon-based light emitters

Silicon (Si)-based light-emitting devices are ideal for use in optoelectronic-integrated-circuit applications because of their low cost, high reliability, and functional versatility. Now, researchers at Musashi Institute of Technology (Tokyo, Japan) and Tohoku University (Sendai, Japan) have successfully embedded germanium (Ge) self-assembled quantum dots in microdisk resonators measuring 2 to 5 µm in diameter to form Si-based light emitters.

The team fabricated the microdisks on silicon-on-insulator substrates and embedded the Ge self-assembled quantum dots inside the disk as light emitters. Optical pumping close to the edge of the microdisks using a 514.5 nm argon-ion laser beam with 0.8 mW of power produced microphotoluminescence over a wavelength range from 1.2 to 1.6 µm at room temperature. The microdisk resonators enhanced the luminescence and formed sharp resonant peaks corresponding to whispering-gallery modes and Fabry-Perot cavity modes. Jinsong Xia and his colleagues attribute wavelengths of light longer than 1.2 µm to the Ge quantum dots and Ge-based structure, and wavelengths shorter than 1.2 µm to Si bulk luminescence. Contact Jinsong Xia at [email protected].