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
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