Electrical, Photoelectrical and Morphological Properties of ZnO Nanofiber Networks Grown on SiO2 and on Si Nanowires

VEGA, NADIA; TIRADO, MONICA; COMEDI, DAVID; RODRIGUES, A.D.; RODRIGUES, TOMÁS; HUGHES, G. M.; GROVENOR, CRM; AUDEBERT, FERNANDO

São Carlos, SP

Conferencia; The 5th Latin American Conference on Metastable and Nanostructured Materials: NANOMAT 2012; 2012

Federal University of São Carlos, UFSCar

ZnO nanofibre networks (NFNs) were grown by vapour transport method on Si-based substrates. One type of substrate was SiO2 thermally grown on Si and another consisted of a Si wafer onto which Si nanowires (NWs) had been grown having Au nanoparticles catalysts. The ZnO-NFN morphology was observed by scanning electron microscopy on samples grown at 600ºC and 720ºC substrate temperature, while an focused ion beam was used to study the ZnO NFN/Si NWs/Si and ZnO NFN/SiO2 interfaces. Photoluminescence, electrical conductance and photoconductance of ZnO-NFN was studied for the sample grown on SiO2. The photoluminescence spectra show strong peaks due to exciton recombination and lattice defects. The ZnO-NFN presents quasi-persistent photoconductivity effects and ohmic I-V characteristics which become nonlinear and hysteretic as the applied voltage is increased. The electrical conductance as a function of temperature can be described by a modified three dimensional variable hopping model with nanometer-ranged typical hopping distances.