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Photoluminescence and time-resolved photoluminescence of star-shaped ZnO nanostructures |
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| Authors: | CP Li ZY Wu LR Ren JP Zhang HB Xu |
| Institution: | a School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing, 100083, China b Institute of High Energy Physics, Chinese Academy of Science, Beijing, 100039, China c Chemistry Institute, Chinese Academy of Science, Beijing, 100080, China d Electron Microscopy Laboratory, and State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China |
| Abstract: | Optical properties of star-shaped ZnO nanostructures were studied. The temperature-dependent photoluminescence (PL) was examined up to fourth-order longitudinal optical (LO) phonon assisted emissions of free excitons and confirmed that the nature of the room temperature PL in ZnO is 1-LO phonon assisted emission of free excitons. Low threshold ultraviolet stimulated emissions (SE) were obtained for our powder samples at room temperature. Picosecond time-resolved PL measurements detected a bi-exponential decay behavior which is strongly dependent on the excitation intensity: the slow decay term decreased faster than the fast decay term as the excitation intensity increased and the emission decays were dominated by the fast one. We also found that the emission decays decreased super-linearly before the appearance of the SE. This behavior may be used to deduce the threshold of SE or lasing. |
| Keywords: | 78 55 Et 78 47 +p 78 45 +h 71 35 -y |
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