Date of Graduation

Summer 2015

Degree

Master of Science in Materials Science

Department

Physics, Astronomy and Materials Science

Committee Chair

Kartik Ghosh

Keywords

nanostructures, Raman spectroscopy, oxide semiconductors, optoelectronics, molecular dynamics simulation

Subject Categories

Materials Science and Engineering

Abstract

ZnO is an n-type semiconductor having a large band gap of 3.37eV. This study optimizes the fabrication process to grow high quality vertically aligned Zinc oxide (VAZO) nanorods on different substrates without catalyst by pulse laser deposition (PLD) technique at high chamber pressure of 0.3 Torr through varying substrate temperature and the number of laser pulses. The nanoparticles deposited at high pressure act as nucleation sites that help in the formation of nanostructures following Volmer Weber model and VS (Vapor-Solid) growth mechanism. X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and photoluminescence (PL) spectroscopy techniques were used to characterize VAZO nanorods. Two sharp ZnO peaks (0002) and (0004) dominate the XRD pattern with high intensity consistent with the ZnO nanorods that are principally oriented along the c-axis. SEM images indicate a regular arrangement of the vertically aligned hexagonal closed pack nano structures of ZnO which is also supported by the presence of E2 (high) and A1 (LO) Raman active modes. A reduction in the defect level peak intensities can be analyzed from the PL spectra as the diameter of the VAZO nanorods has been increased, by changing the temperature and also been effected by annealing treatment. Molecular dynamics simulation studies were performed using LAMMPS software for better interpretation of the properties of VAZO nanorods annealed at different temperatures in oxygen and hydrogen atmosphere.

Copyright

© Priyanka Karnati

Campus Only

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