Evaluating the Quantum Confinement Effect of Isolated ZnO Nanorod Single-Quantum-Well Structures Using Near-Field Ultraviolet Photoluminescence Spectroscopy

Using low-temperature near-field spectroscopy, we obtained spatially and spectrally resolved photoluminescence (PL) images of individual ZnO nanorod single-quantum-well structures (SQWs) with a spatial resolution of 20 nm. We observed the dependence of the quantum confinement effect of the PL peak on the well width (L aw), from which the linewidths of near-field PL spectra of ZnO nanorod SQWs (L aw = 2.5 and 3.75 nm) were determined to be as narrow as 3 meV. However, near-field PL spectra of individual SQWs with L aw = 5.0 nm exhibited two PL peaks, presumably due to strains or defects in the ZnMgO in the nanorod SQWs. 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.The work at POSTECH was supported by the National Creative Research Initiative Project, Korea and AOARD 05-84 (Quotation No. FA5209-05-T0369), United States