InGaAs quantum dot superlattice with vertically coupled states in InGaP matrix

Abstract

We report the formation of vertically coupled states in a 20-stack InGaAs quantum dot (QD) superlattice with GaAs spacer layers in an InGaP matrix. The InGaAs QD superlattices in the InGaP matrix have good optical properties even though the interdot spacing is reduced to 4.5 nm. We confirmed the vertically coupled states from the excitation power dependence in photoluminescence (PL) measurements. The PL peak of a QD superlattice shifts to a shorter wavelength as the excitation power is increased. The blue-shifted energy of the PL peak is 10 meV for a QD superlattice with an interdot spacing of 4.5 nm, whereas the blue shift is not observed for a multistacked QD structure with an interdot spacing of 17 nm. The vertically coupled states induce a blue shift in the PL peak wavelength as the excitation power density is increased. The vertical energy transfer between InGaAs QDs in an InGaP matrix is very attractive for use in solar cell devices.