Date of Graduation

Fall 2021

Degree

Master of Science in Materials Science

Department

Physics, Astronomy, and Materials Science

Committee Chair

Kartik Ghosh

Keywords

pulsed laser annealing, thin films, ZnO, semiconductor defects, photoluminescence, electrical conductivity, molecular dynamic simulation

Subject Categories

Semiconductor and Optical Materials

Abstract

ZnO thin films have attracted great attention recently due to their unique electronic and optical properties. However, for proper implementation of ZnO in electronic devices it is necessary to understand the role of native point defects present inside the material as these wide bandgap semiconductors are inherently n-type due to oxygen vacancies. The objective is to control the electronic and optical properties of ZnO thin films through pulsed laser annealing (PLA). Thin films of ZnO have been grown on different substrates using pulsed laser deposition. Then PLA of the films are done by changing laser parameters (energy, frequency, pulse width, number of shots). Structural quality of the annealed films is investigated using X-ray diffraction, electron microscopy, Raman spectroscopy. Optoelectronic properties of the PLA films are investigated using photoluminescence spectroscopy and electrical characterization. It was shown from the experimental results that the conductivity can be changed through the modification of point defects (vacancies and interstitials) with the selection of proper annealing parameters. The photoluminescence spectroscopy showed for a controlled number of laser shots and energy, peak intensities associated with defects (vacancies and interstitials) are decreased while area of band emission peaks increased. Additionally, the structural properties of annealed ZnO by simulating the PLA process through MD simulation were investigated. The results were also further evidence that laser irradiation can be a useful technique for semiconductor material modification.

Copyright

© Md Abu Zobair

Open Access

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