Optical Properties Of Post-annealed Zinc Oxide (ZnO) Thin Films Synthesized By Pulsed Laser Deposition (PLD)
Bhawana Joshi, Santanu Ghosh, Pankaj Srivastava
Volume 2, Issue 9, Page 581-586, Year 2017 | DOI: 10.5185/amp.2018/735
Keywords: ZnO thin films, pulsed laser deposition, optical properties, photoluminescence, deep level defects.
Abstract: In the present work, ZnO thin films deposited by pulsed laser deposition (PLD) technique have been characterized structurally and optically after post-deposition annealing. As-deposited thin films were annealed in the ambient atmosphere for different annealing temperatures of 2000C, 4000C, 6000C and 8000C. X-ray diffraction (XRD) technique was used for structure analysis and elucidated that both as-deposited and annealed films were of good structural quality and highly oriented towards c-axis. UV-Vis spectrophotometer was used to study the transmittance and optical band gap of as-deposited and annealed films. Photoluminescence (PL) technique was used to investigate the photoluminescent properties of all the films. It was found that ZnO thin films were highly transparent in nature and showed two emissions in PL spectra. One was attributed to near band edge (NBE) emission and the other was the broad deep-level (DL) emission. There was a significant change in the photoluminescent properties of the films and it was observed that the intensity of the DL emission increased significantly with the increase in the annealing temperature. The change in DL emission is attributed to the change in defect states inside the band gap of the annealed films. From the present work, it is inferred that the properties of the ZnO films can be tuned by post-deposition annealing for various applications such as optical and optoelectronic devices. Copyright © 2017 VBRI Press.