Direct imaging of the visible emission bands from individual ZnO nanowires by near-field optical spectroscopy.
Room-temperature photoluminescence (PL) measurements have been performed on single-crystal ZnO nanowires grown on SiO2/Si and quartz substrates by the vapor transport method using Au as a catalyst. Two emission bands are apparent, one in the UV spectral region around 380 nm (3.26 eV) associated with exciton recombination processes and a much broader structure in the visible range from 420 to 700 nm, which exhibits two distinct peak-like features around 520 and 590 nm (2.38 and 2.10 eV). Spectrally resolved scanning near-field optical microscopy (SNOM) of single ZnO nanowires have been performed for a direct imaging of the PL emission with spatial resolution below 100 nm. SNOM results provide evidence that the yellow emission band observed at 590 nm is a unique property of the ZnO nanowires, being most likely related to radiative recombination processes associated with Au impurities introduced during the catalytic growth.
Güell
F
F
Departament d'Electrònica, Universitat de Barcelona, C/Martíi Franquès 1, E-08028 Barcelona, Catalunya, Spain. frank@el.ub.es
Ossó
J O
JO
Goñi
A R
AR
Cornet
A
A
Morante
J R
JR