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Plasmonic switching in Au functionalized GaN nanowires in the realm of surface plasmon polatriton propagation: A single nanowire switching device

Photoresponse of Au nanoparticle functionalized semiconducting GaN (Au-GaN) nanowires is reported for an optical switching using 532 excitation. Wide band gap GaN nanowires are grown by catalyst assisted chemical vapour deposition technique and functionalized with Au in the chemical route. Au-GaN nanowires show surface plasmon resonance (SPR) mode of Au nanoclusters around 550 nm along with characteristic band for GaN around 365 nm. An optical switching is observed for Au-GaN nanowires with a sub-band gap excitation of 532 nm suggesting possible role of surface plasmon polariton assisted transport of electron in the system. Role of band conduction is ruled out in the absence of optical switching using 325 nm excitation which is higher in energy that the reported band gap of GaN about 3.4 eV (365 nm) at room temperature. A finite amount of interband contribution of Au plays an important role along with the inter-particle separation. The switching device is also successfully tested for a single GaN nanowire functionalized with Au nanoclusters. A resistivity value of 0.05 Ohm-cm is measured for surface plasmon polariton assisted electrical transport of carrier in the single GaN nanowire.