Title: | Peculiar near-band-edge emission of polarization-dependent XEOL from a non-polar a-plane ZnO wafer |
Authors: | Lin, Bi-Hsuan Wu, Yung-Chi Chen, Huang-Yeh Tseng, Shao-Chin Wu, Jian-Xing Li, Xiao-Yun Chen, Bo-Yi Lee, Chien-Yu Yin, Gung-Chian Chang, Shih-Hung Tang, Mau-Tsu Hsieh, Wen-Feng 光電工程學系 Department of Photonics |
Issue Date: | 5-Feb-2018 |
Abstract: | Polarization-dependent hard X-ray excited optical luminescence (XEOL) was used to study not only the optical properties but also the crystallographic orientations of a non-polar a-plane ZnO wafer. In addition to a positive-edge jump and extra oscillations in the near-band-edge (NBE) XEOL yield, we observed a blue shift of the NBE emission peak that follows the polarization-dependent X-ray absorption near-edge structure (XANES) as the X-ray energy is tuned across the Zn K-edge. This NBE blue shift is caused by the larger X-ray absorption, generating higher free carriers to reduce the exciton-LO phonon coupling, which causes a decrease in the exciton activation energy. The extra oscillations in XANES and XEOL as the polarization is set parallel to the c-axis is attributed to simultaneous excitations of the Zn 4p - O 2p pi-bond along the c-axis and the bilayer sigma-bond, whereas only the sigma-bond is excited when the polarization is perpendicular to the c-axis. The polarization-dependent XEOL spectra can be used to determine the crystallographic orientations. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement |
URI: | http://dx.doi.org/10.1364/OE.26.002731 http://hdl.handle.net/11536/144545 |
ISSN: | 1094-4087 |
DOI: | 10.1364/OE.26.002731 |
Journal: | OPTICS EXPRESS |
Volume: | 26 |
Begin Page: | 2731 |
End Page: | 2739 |
Appears in Collections: | Articles |