Excitonic lasing of strain-free InP(As) quantum dots in AlInAs microdisk

Formation, emission, and lasing properties of strain-free InP(As)/AlInAs quantum dots (QDs) embedded in AlInAs microdisk (MD) cavity were investigated using transmission electron microscopy and photoluminescence (PL) techniques. In MD structures, the QDs have the nano-pan-cake shape with the height of ∼2 nm, the lateral size of 20–50 nm, and the density of ∼5 × 109 cm−2. Their emission observed at ∼940 nm revealed strong temperature quenching, which points to exciton decomposition. It also showed unexpected type-I character, indicating In-As intermixing as confirmed by band structure calculations. We observed lasing of InP(As) QD excitons into whispering gallery modes in MD having the diameter of ∼3.2 μm and providing a free spectral range of ∼27 nm and quality factors up to Q∼13 000. Threshold of ∼50 W/cm2 and spontaneous emission coupling coefficient of ∼0.2 were measured for this MD-QD system.