ZnO nanowire co-growth on SiO2 and C by carbothermal reduction and vapour advection

VEGA, NADIA; WALLAR R; CARAM, JORGE; GRINBLAT, GUSTAVO; TIRADO, MONICA; LAPIERRE, RAY; COMEDI, DAVID

NANOTECHNOLOGY

IOP PUBLISHING LTD

Año: 2012 vol. 23 p. 275602 - 27560211

0957-4484

Vertically aligned ZnO nanowires (NW) were grown on Au-nanocluster seeded amorphous SiO2 films by the advective transport and deposition of Zn vapours obtained from the carbothermal reaction of graphite and ZnO powders. Both the NW volume and visible-to-UV photoluminescence ratio were found to be strong functions of, and hence could be tailored by, the (ZnO+C) source-SiO2 substrate distance. We observe C flakes on the ZnO NW/SiO2 substrates which exhibit short NWs that developed on their both sides. The SiO2 and C substrates/NW interfaces were studied in detail to determine growth mechanisms. NWs on Au seeded SiO2 was promoted by a rough ZnO seed layer whose formation was catalized by the Au clusters. In contrast, NWs grew without any seed on C. A correlation comprising three orders or magnitude between the visible-to-UV PL intensity ratio and the NW volume is found, which results from a characteristic Zn partial pressure profile that fixes both O deficiency defect concentration and growth rate.