CHARACTERIZATION OF A SINGLE-LAYER QUANTUM-WIRE STRUCTURE GROWN DIRECTLY ON A SUBMICRON GRATING

A single AlGaAs/GaAs quantum well (QW)/quantum wire (QWR) structure was grown by metalorganic vapor phase epitaxy on a submicron period grating of V grooves. High resolution transmission electron microscopy studies of the sample identifies three regions of the QW; between the grooves, approximately 3.5 nm thick and oriented along (100), on the sidewalls of the V groove slightly thinner and oriented along {111}. At the bottom of the groove an approximately 70 nm wide crescent shaped region forms a QWR. In addition, a vertical quantum well (VQW) extends from the bottom of each V groove in the GaAs substrate to the surface. The luminescence spectra of the sample are dominated by a peak originating in the QW, with additional peaks of the QWR, the VQW and the AlGaAs barrier. The striped nature of the sample is revealed in the top view cathodoluminescence (CL) images of all four peaks. In side view CL images, the QWR emission appears spot like, whereas the emission of the VQW is elongated in the direction perpendicular to the surface. Photoluminescence excitation spectroscopy reveals that the main source for excitation in the QWR comes from the VQW, even though a small contribution comes from the QW.