High degree of polarization of the near-band-edge photoluminescence in ZnO nanowires
1 Institut d'Electronique Fondamentale, Université Paris Sud XI, UMR 8622 CNRS, 91405 Orsay, France
2 CNR-IDASC SENSOR Lab., University of Brescia, Brescia, Italy
Nanoscale Research Letters 2011, 6:501 doi:10.1186/1556-276X-6-501Published: 19 August 2011
We investigated the polarization dependence of the near-band-edge photoluminescence in ZnO strain-free nanowires grown by vapor phase technique. The emission is polarized perpendicular to the nanowire axis with a large polarization ratio (as high as 0.84 at 4.2 K and 0.63 at 300 K). The observed polarization ratio is explained in terms of selection rules for excitonic transitions derived from the k·p theory for ZnO. The temperature dependence of the polarization ratio evidences a gradual activation of the XC excitonic transition.
PACS: 78.55.Cr, 77.22.Ej, 81.07.Gf.