Takashi YATSUI^1,*, Motoich OHTSU^1,2, Sung Jin AN³, Jinkyoung YOO³ and Gyu-Chul YI³

¹Solution-Oriented Research for Science and Technology (SORST), Japan Science and Technology Agency, 687-1 Tsuruma, Machida, Tokyo 194-0004, Japan
²School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
³National CRI Center for Semiconductor Nanorods and Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), San 31 Hyoja-dong, Pohang, Gyeongbuk 790-784, Korea

(Received November 15, 2005; Accepted January 20, 2006)

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.

Key words: ZnO, nanorod, single-quantum-well structures, quantum confinement effect

^*E-mail address: yatsui@ohtsu.jst.go.jp