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 homoepitaxial films and advanced micro-fabrication processes. The epitaxial structure consists InGaN/GaN multi-quantum wells (MQWs) sandwiched between AlGaN/GaN InAlN/GaN superlattices as cladding layers for optical confinement. Due to lattice-matched growth low dislocations, an internal quantum efficiency ∼40% is attained, while sidewalls etched 8 µm-diameter microdisks patterned by microsphere lithography optically smooth promote formation whispering-gallery modes (WGMs) within circular cavities. Optically pumped lasing threshold ∼5.2 mJ/cm 2 (Q) factor ∼3000 at dominant wavelength 436.8 nm has been observed. also support electroluminescent operation, demonstrating WGMs consistent photoluminescence spectra finite-difference time-domain (FDTD) simulations.