Characterization of InP nanowires grown on non-single-crystal platforms

InP nanowires were grown by metalorganic chemical vapor deposition (MOCVD) on a quartz substrate that was covered with a layer (100 nm) of non-single crystal hydrogenated silicon (Si:H) demonstrating that single crystalline platforms are not a requirement for single crystal semiconductor nanowire growth. Scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL), Raman spectroscopy and Cathode luminescence (CL) were used to characterize the structural and optical properties of the nanowires. The nanowires grew in random directions with uniform size distribution and with high density. Two different crystallographic habits were found to grow as has been reported previously and the suggestion that the differing crystallographic habits are due to distinct wurtzite and zincblende crystal structures1 is further substantiated by the XRD profile presented in this paper. The XRD profile suggests that nanowires either having hexagonal-close-packed or face-centered cubic lattice are present. The Raman spectrum shows peaks associated with transverse optical (TO) and longitudinal optical (LO) branches of InP. The Raman peaks closely match those of bulk InP. CL of a single InP nanowire was to study the variations in luminescence along the long axis of the tapered nanowire from the base (~250 nm in diameter) to the tip (~10 nm in diameter), however no substantial variation in luminescence was observed along the long axis of the nanowires. Microscopic carrier recombination dynamics of the nanowires will be discussed with the view towards nanowire-based optical sensors.