Dissertation
EXCIMER LASER INTERACTION WITH ZINC OXIDE
Doctor of Philosophy (PhD), Washington State University
01/2011
Handle:
https://hdl.handle.net/2376/3522
Abstract
When single crystal ZnO is exposed to 193-nm laser photons in vacuum at fluences below 100 mJ/cm2, isolated Zn vacancies are produced due to the emission of energetic Zn+. The pairwise formation of Zn vacancies and Zn+ interstitials is attributed to the photochemical excitation of anti-bonding Zn-O bonds. Interstitial Zn+ diffuses to the surface where it is loosely bound to the surface--often atop a photoionizable electron trap; adsorbed Zn+ is emitted when the underlying trap is photoionized. Isolated Zn vacancies also diffuse following the laser pulse. These electron traps can reduced the near-surface free carrier concentration by as much as a factor of five on irradiated samples.
At fluences between 150 and 200 mJ/cm2, 193-nm irradiation produces sustained emission of ionic and neutral species. The near-surface region of the irradiated sample becomes increasingly metallic and zinc rich. At fluences in the 250-300 mJ/cm2 range, a slower component of the Zn+ emission appears which is attributed to the excitation of an auto-ionizing state at 12.77 eV. The same excitation also yields Zn atomic light emission, predominately due to transitions on the triplet manifold. Rydberg Zn* atoms in high-lying quantum states appear at a threshold fluence of about 330 mJ/cm2. At fluences greater than or equal to 2.0 J/cm2, atomic light emission due to optical breakdown is observed.
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Details
- Title
- EXCIMER LASER INTERACTION WITH ZINC OXIDE
- Creators
- Enamul Haque Khan
- Contributors
- J. Thomas Dickinson (Advisor)Yi Gu (Committee Member)Mark G. Kuzyk (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Physics and Astronomy, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 147
- Identifiers
- 99900581456501842
- Language
- English
- Resource Type
- Dissertation