Whispering-gallery mode InGaN microdisks on GaN substrates

Microdisks fabricated with III-nitride materials grown on GaN substrates are demonstrated, taking advantage of the high material quality of homoepitaxial films and advanced micro-fabrication processes. The epitaxial structure consists of InGaN/GaN multi-quantum wells (MQWs) sandwiched between AlGaN/GaN and InAlN/GaN superlattices as cladding layers for optical confinement. Due to lattice-matched growth with low dislocations, an internal quantum efficiency of similar to 40% is attained, while the sidewalls of the etched 8 mu m-diameter microdisks patterned by microsphere lithography are optically smooth to promote the formation of whispering-gallery modes (WGMs) within the circular optical cavities. Optically pumped lasing with low threshold of similar to 5.2 mJ/cm(2) and quality (Q) factor of similar to 3000 at the dominant lasing wavelength of 436.8 nm has been observed. The microdisks also support electroluminescent operation, demonstrating WGMs consistent with the photoluminescence spectra and with finite-difference time-domain (FDTD) simulations. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

Microdisks fabricated with III-nitride materials grown on GaN substrates demonstrate high material quality of homoepitaxial films and advanced micro-fabrication processes. The microdisks achieve an internal quantum efficiency of around 40% and exhibit low threshold optically pumped lasing at the dominant lasing wavelength.