Radiative recombination in pseudomorphic InGaAs/GaAs quantum wires grown on nonplanar substrates

Abstract

The concept of fabricating quantum wires (QWRs) by growing quantum wells (QWLs) over non-planar substrates is extended to the pseudomorphic system In 0.2Ga 0.8As/AlGaAs. The InGaAs QWR is grown as the active region in a laser structure between graded Al x Ga 1− x As ( x = 0.2−0.7) cladding layers on a V-grooved GaAs substrate. The different spectral components of the luminescence stemming from the AlGaAs barriers, the top quantum well on the ridge in between the grooves ( L = 7 nm, which is about half the critical thickness), the sidewalls and the InGaAs wire itself can be unambiguously attributed to the respective regions using spatially resolved cathodoluminescence (CL). The wire emits at T = 5 K at a peak wavelength of λ = 955 nm (1.298 eV) with a full width at half maximum of 14 meV. From time-resolved experiments (over all time resolution ≈ 350 ps) we find a recombination time constant of 1.0 ns. This value compares well with carrier lifetimes found for InGaAs quantum wells of similar thickness and shows that the recombination is dominated by radiative processes.