Lasing via excited state of type A InP/GaInP quantum dots embedded in microdisks

We describe the growth, material characterization, and lasing of InP/GaInP quantum dot (QD) microdisks (diameter D = 2.2 μm, quality factor Q ∼ 9000) with an emission lasing line of 693 nm (77 K). We demonstrate that MOVPE growth can result in two types of InP/GaInP QDs, differing in height (type A h ∼ 5-10 nm, type B h ∼ 20 nm), whose emission has different decay lifetimes (τ A = 0.6 ns, τ B = 2.4 ns). We show, importantly for technological microlasing applications, that lasing occurs via the excited states of type A QDs, as inferred from a number of experimental results: power-dependent photoluminescence, time-resolved experiments, and temperature dependence of the generation threshold.