Structural and Optical Characterization of a Quantum Wire

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We have demonstrated that GaAs quantum wires were naturally formed on vicinal GaAs (110) surfaces misoriented toward (111) A using MBE.These naturally formed quantum wires were induced by the formation of coherently aligned giant growth steps and temarkable thickness modulation of GaAs layrs at giant step edges. Transmission electron microscopy (TEM), atomic force microscopy and photoluminescence (PL) measurements consistently confirmed this formation of quantum wires. Although the PL strongly polarized parallel to the wire direction was observed for these quantum wires, the PL was rether broad and is thought to be due to the nonuniform quantum wire structures. To improve the uniformity, we employed the two-step growth and growth interruption method. More red-shifed and narrower PL peaks were abserved, indicating the thicker GaAs layrs at the step edges and the improved uniformity of the quantum wire structures.In order to know the luminescence from single quantum wires, we carried out micro-PL and scanning cathodoluminescence measurements. Sharp luminescence peaks were observed for single quantum wires. These sharp peaks are considered to come from the localized excitions.We also grow InAs and InGaAs layrs on the vicinal (110) surfaces with giant steps and found that InAs and InGaAs quantum wires and dots were formed at the giant step edges.