標題: Room temperature excitonic dynamics of non-polar a-plane ZnO epifilms
作者: Lin, Ja-Hon
Liu, Wei-Rein
Lin, Yi-Chin
Su, Hsing-Jung
Chen, Hou-Ren
Tsai, Chih-Ya
Chen, Yao-Hui
Hsieh, Wen-Feng
光電工程學系
Department of Photonics
公開日期: 九月-2016
摘要: Pump polarization dependent carrier dynamics, particularly excitonic dynamics, of non-polar a-plane zinc oxide (ZnO) epifilms with two different thicknesses were investigated using time resolved measurements. Unlike the electron and hole dynamics through the above-bandgap excitation, transient differential reflectance (TDR) traces revealed similar trends under two orthogonal pump polarization conditions relative to the c-axis (E-pu +/- c and E-pu vertical bar vertical bar c) of a-ZnO around near-exciton-resonance excitation. By means of a band diagram, the bandgap renormalization (BGR) effect can be reasonably explained by the screening of the Coulomb potential energy due to the accumulation of relaxed free carriers that were initially excited through the absorption of two cascaded pump photons via the excitonic level, a process known as two photon absorption (TPA). Thus, the modulation depths of the TPA around zero time delay, due to simultaneous absorption of one pump and one probe photon via the excitonic level, increased linearly with the pump fluence, proportional to the modulation depth resulting from the BGR effects. (C) 2016 Author(s).
URI: http://dx.doi.org/10.1063/1.4964149
http://hdl.handle.net/11536/132678
ISSN: 2158-3226
DOI: 10.1063/1.4964149
期刊: AIP ADVANCES
Volume: 6
Issue: 9
顯示於類別:期刊論文