Linearly polarized and time-resolved cathodoluminescence study of strain-induced laterally ordered (InP)2/(GaP)2 quantum wires

The optical properties of (InP)2/(GaP)2 bilayer superlattice (BSL) structures have been examined with linearly polarized cathodoluminescence (CL), time-resolved CL spectroscopy, and cathodoluminescence wavelength imaging. An In and Ga composition modulation of ∼18% forms during the metalorganic chemical vapor deposition growth of short period (InP)2/(GaP)2 bilayer superlattices. Transmission electron microscopy showed a period of ∼800 A along the [110] direction, resulting in coherently strained quantum wires. A strong excitation dependence of the polarization anisotropy and energy of excitonic luminescence from the quantum wires was found. The results are consistent with a phase-space and band filling model that is based on a k⋅p and two dimensional quantum confinement calculation which takes the coherency strain into account. CL images reveal that defects in the BSL originate from the GaAs substrate and/or the initial stages of InGaP growth. The effects of defects on the band filling, carrier relaxation...