Photoluminescence characterization of InGaAs/InP quantum dots

The photo-excited carrier distribution and radiative recombination efficiency in dryetched quantum well dots (QWDs) with diameters down to 80 nm have been investigated by photoluminescence (PL) spectroscopy and cathodoluminescence (CL) imaging. The quantum well dots were fabricated from lattice-matched single or multiple quantum well heterostructures with InGaAs well thicknesses ranging from 2 to 15 nm. Low temperature CL imaging indicated dot-to-dot variation of emission intensity. The PL efficiency exhibits no significant reduction for dot sizes larger than 170 nm. But for dot diameters smaller than ∼100 nm, the PL intensity is not detectable. Such diminution of PL intensity is attributed to side wall damage due to reactive ion etching. For dot diameters smaller than 300 nm, PL peak energies shift to higher values, reaching a blue shift of ∼ 3 meV for 128 nm diameter GSMBE grown dots and ∼10 meV for 130 nm diameter MOCVD grown dots.