Photoluminescence spectra of ZnO thin film and nanorod
| Autor: | Hsuan-I Wu, 吳宣誼 |
|---|---|
| Rok vydání: | 2019 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 107 By using photoluminescence spectroscopy (PL), we have studied the properties (Cystal quality, Exciton properties, Energy level, Band gap energy fuction of temperature and the signal caused by the phonon) of the nanorod ZnO whose annealed condition were different (As-grown, Annealed 600℃and 700℃) and the thin film ZnO temperature whose Zn/Oxygen ratio were different(more Zn or O in the crystal). In the low temperature PL spectra of the all sample, it not only appeared a strong and sharp near band gap emission (NBE) signal around 3.36 eV, but also appeared a wide signal from 1.8 to 2.4 eV caused by the fact of the electron transition in the crystal defect energy level (DE) and meanwhile coulpling several phonon (Phonon replica) at the same time. The intensity ration of NBE to DE could reflect the crystal quality of the sample. From the low temperature PL spectra we found that the ratio of nanorod sample would increases as procedure annealing, and would keep increased as the annealed teprature increased; thin film sample would increases as Zn/Oxygen ratio decreased. Moreover, the DE of thin film appeared the “wave like” curves which caused by the influence of the phonon. The Zn-rich thin film sample also appeared the “wave like” curves that all the other sample didn’t have: this is caused by the unique defect level and acceptor level existed in that sample. The value of the bad gap energy of variety temperature could be found from the temperature dependent spectra. Manoogian–Wooley’s (MW) model indicated that the phenomenon of the red shift of the band gap energy of the semiconductor as temperature increased is mainly caused by thermal expansion and phonon-coupling effect. The degree of the red shift in low temperature would be more obvious if the effect of thermal expansion is hard. We finally found that the band gap energy of nanorod ZnO didn’t influence by this effect throughout the fitting of MW’s model. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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