ZnO nanowires for solid state lighting:: from epitaxy and collective integration to optical and electrical characterization

We report on the epitaxy of vertically aligned ZnO nanowires (NWs), the collective integration technology of these nanowires and their optical and electrical characterizations. ZnO based nanowires are grown mainly on sapphire substrates by metal-organic vapour phase epitaxy (MOVPE). Photoluminescence spectra at 4 K exhibit strong excitonic peaks at around 380 nm without green luminescence band, showing the low deep radiative defect density. Technological processes have been developed both for mineral and organic integrations of the as-grown nanowires. Photoconducting properties in the UV-visible range have been investigated through collective electrical contacts. The electrical transport properties of vertically integrated single nanowires have also been investigated by current sensing AFM measurements. A comparison of the PL spectra at 300 K of the as-grown and integrated nanowires has shown no significant impact of the integration process on the crystal quality of the nanowires.