Photoluminescence of strain-induced coupled InGaAs/GaAs quantum-dot pairs

Coupled quantum dot-pairs were fabricated by growing InP self-assembled isl ands as stressors on InGaAs/GaAs double quantum wells. State filling in the photoluminescence spectra was used to resolve the quantum states in the co upled dots. The total strain field below the stressor decays exponentially with a penetration depth of about 25 nm, within which a dot pair can be fab ricated. Strong coupling is observed at a barrier width less than 4 nm sepa rating the dot-pair. By increasing the indium composition in the lower well in order to match its dot level with one in the upper dot with identical q uantum numbers, resonant coupling between the electron states with identica l quantum numbers in the two dots can be achieved. Decoupling of the hole s tates and exchange of the electron bonding states from dominating the upper dot to the lower one are clearly resolved from the state energies and thei r spacings.