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We report on the photoluminescence properties of ZnO nanowires treated with a mild Ar plasma. The nanowires exhibited stable and strong enhancement of the near-band-edge emission and quenching of the deep level emission. The low temperature PL revealed a strong hydrogen donor-bound-exciton line in the plasma-treated samples indicating unintentional incorporation of hydrogen during the plasma treatment. To confirm the results, hydrogen was implanted into the ZnO nanowires with a low ion energy of 600 eV and different fluences. The observed result can be related to the passivation of deep centers by hydrogen. The absolute photoluminescence intensity measured by an integrating sphere showed stable and strong UV emission from the treated samples even after several weeks.

High material quality InP-based multilayer nanopillar (NP) arrays are fabricated using a combination of self-assembly of silica particles for mask generation and dry etching. In particular, the NP arrays are made from user-defined epitaxial multilayer stacks with specific materials and layer thicknesses. An additional degree of flexibility in the structures is obtained by changing the lateral diameters of the NP multilayer stacks. Pre-defined NP arrays made from InGaAsP/InP and InGaAs/InP NPs are then used to generate substrate-free nanodisks of a chosen material from the stack by selective etching. A soft-stamping method is demonstrated to transfer the generated nanodisks with arbitrary densities onto Si. The transferred nanodisks retain their smooth surface morphologies and their designed geometrical dimensions. Both InP and InGaAsP nanodisks display excellent photoluminescence properties, with line-widths comparable to unprocessed reference epitaxial layers of similar composition. The multilayer NP arrays are potentially attractive for broad-band absorption in third-generation solar cells. The high optical quality, substrate-free InP and InGaAsP nanodisks on Si offer a new path to explore alternative ways to integrate III-V on Si by bonding nanodisks to Si. The method also has the advantage of re-usable III-V substrates for subsequent layer growth.

ZnO nanowire arrays were synthesized on zinc foil by a simple thermal evaporation process at relatively low temperature. Morphology and size controlled synthesis of the ZnO nanostructures was achieved by variation of the synthesis temperature, reaction time and the surface roughness of the substrate. A gas-solid and self-catalytic liquid-solid mechanism is proposed for the growth of nanowires at different temperatures. High-resolution transmission electron microscopy (HRTEM) showed that the as-grown nanowires were of single crystal hexagonal wurtzite structure, growing along the [101] direction. Photoluminescence exhibited strong UV emission at ∼382 nm and a broad green emission at ∼513 nm with 325 nm excitation. Raman spectroscopy revealed a phonon confinement effect when compared with results from bulk ZnO. The nanowire arrays also exhibited a field emission property.

Large-scale ZnO nanowire arrays with honeycomb-like micropatterns have been synthesized by a surfactant assisted soft chemical approach. Sol–gel-derived ZnO thin film with crystallographic orientation along the c axis was used as a substrate for the growth of ZnO nanowires. The micropatterned arrays of ZnO nanowires also exhibited strong crystallographic orientation along the c axis. Experimental parameters were varied to explore the possible growth mechanism of the nanowires as well as the micropatterned arrays formed by the ZnO nanowires. The room temperature photoluminescence studies revealed that the ZnO nanowire arrays exhibited a strong UV emission peak at ~3.22 eV ascribed to the band edge emission.