Near-field measurement of spectral anisotropy and optical absorption of isolated ZnO nanorod single-quantum-well structures

We report low-temperature near-field spectroscopy of isolated ZnO∕ZnMgO single-quantum-well structures (SQWs) on the end of ZnO nanorod to define their potential for nanophotonics. First, absorption spectra of isolated ZnO∕ZnMgO nanorod SQWs with the Stokes shift as small as 3meV and very sharp photoluminescent peaks indicate that the nanorod SQWs are of very high optical quality. Furthermore, we performed polarization spectroscopy of isolated ZnO SQWs, and observed valence-band anisotropy of ZnO SQWs in photoluminescence spectra directly. Since the exciton in a quantum structure is an ideal two-level system with long coherence times, our results provide criteria for designing nanophotonic devices.