Probing the exciton-phonon coupling strengths of O-polar and Zn-polar ZnO wafer using hard X-ray excited optical luminescence

Thetemperature-dependent hardX-ray excited optical luminescence (XEOL) spectroscopy was used to study theoptical properties of O andZn polarity of a c-plane single crystalZnO wafer. By analyzing the XEOL andXRD, we found an unprecedentedblue shift of the freeexciton transition with increasing the excited carrier density as tuning theX-ray energy across theZn K-edge, and the O-polar face possesses better crystal structure than the Zn-polar one. This spectralblue shift is attributed to the Coulomb screening of the spontaneous polarization by the excited free carriers that result in decreasing the exciton-phonon Fr öhlich interaction to reduceexciton binding energy.

Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: Bi-Hsuan Lin, Huang-Yeh Chen, Shao-Chin Tseng, Jian-Xing Wu, Bo-Yi Chen, Chien-Yu Lee, Gung-Chian Yin, Shih-Hung Chang, Mau-Tsu Tang and Wen-Feng Hsieh Source Type: research