Morphology and optical properties of strained InGaAs quantum wires

Abstract

Strained InGaAs quantum wires have been grown on holographically-patterned (100) GaAs substrates using alternating molecular beam epitaxy. Transmission electron micrographs reveal that the initial grating has rough sidewalls from wet-etching, but they are smoothed by the epilayers within about 100 Å. The growth conditions favor the slow-growth plane controlling the rate of planarization of the grating. The low temperature photoluminescence from the quantum wire sample exhibits two peaks; the high intensity peak centered at 1.417 eV is attributed to the quantum wires at the bottom of the grating, and the lower intensity peak at 1.445 eV is attributed to the sidewall quantum wells. This assignment is verified by growing two additional samples that had identical growth conditions with the exception of a high temperature growth pause after the deposition of the InGaAs layer to promote surface migration and/or desoprtion from the sidewalls. The quantum wire/quantum well peak intensity ratio is 40:1 for the sample with the growth pause compared to 6:1 for the sample without a growth pause.