Near-field scanning optical microscopy of ZnO nanopatterns fabricated by micromolding in capillaries

We report near-field scanning optical microscopy (NSOM) studies of 300-nm-wide ZnO nanopatterns fabricated by micromolding in capillary technique using a sol-gel route. Atomic force microscopy and scanning electron microscopy show that the patterns are continuous with uniform linewidths. Simultaneous topography and optical signal collected in NSOM scans exhibit nanoscale photoluminescence intensity distribution in the ZnO nanopatterns. The nanoscale spectral mapping shows very broad defect-induced green-yellow-red luminescence bands, at room temperature, when excited with a 514.5-nm Ar-ion laser. Our analyses demonstrate that spatially resolved ZnO luminescence features with an optical resolution of ≤300 nm can be obtained with NSOM while operating in collection mode, and underscore the need to couple nanoscale physical characterization with functional properties at the same scale.