Near-field optical spectroscopy of single GaAs quantum wires

The nanoscopic room temperature optical properties of single quantum wires are characterized by a combination of near-field photoluminescence and photoluminescence excitation spectroscopy, Single GaAs quantum wires with a 50 nm lateral dimension are grown at the edge of 15 nm high mesa stripes on patterned GaAs(311) surfaces, Wire formation relies on the preferential migration of Ga atoms from a GaAs layer on the mesa top and bottom towards the sidewall, Spatially resolved photoluminescence spectra separate quantum wire and quantum well emission and image the diffusion of photoexcited carriers into the wires. Photoluminescence excitation spectra give insight into the absorption spectrum of the wires and the spectral position of different interband transitions in the one-dimensional carrier system. They allow the change in local thickness of the GaAs quantum well due to the migration process to be monitored directly with subwavelength spatial resolution. Both the trapping of carriers into the wire and the detrapping of carriers generated within the wire into the surrounding quantum well states are separately resolved. (C) 1997 by John Wiley & Sons, Ltd.