Structural and electrooptical characteristics of quantum dots emitting at 1.3 mu m on gallium arsenide

We present a comprehensive study of the structural and emission properties of self-assembled InAs quantum dots emitting at 1.3 mum. The dots are grown by molecular beam epitaxy on gallium arsenide substrates. Room-temperature emission at 1.3 mum is obtained by embedding the dots in an InGaAs layer. Depending on the growth structure, dot densities of 1-6 x 10(10) cm(-2) are obtained. High dot densities are associated with large inhomogeneous broad enings, while narrow photoluminescence (PL) linewidths are obtained in low- density samples. From time-resolved PL experiments, a long carrier lifetime of approximate to1.8 ns is measured at room temperature, which confirms th e excellent structural quality. A fast PL rise (tau (rise) = 10 +/-2 ps) is observed at all temperatures, indicating the potential for high-speed modu lation. High-efficiency light-emitting diodes (LEDs) based on these dots ar e demonstrated, with external quantum efficiency of 1% at room temperature. This corresponds to an estimated 13% radiative efficiency. Electroluminesc ence spectra under high injection allow us to determine the transition ener gies of excited states in the dots and bidimensional states in the adjacent InGaAs quantum well.