Photosensitivity of nanocrystalline ZnO films grown by PLD

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Abstract

We have studied the properties of ZnO thin films grown by laser ablation of ZnO targets on (0 0 0 1) sapphire (Al2O3), under substrate temperatures around 400 degrees C. The films were characterized by different methods including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and atomic force microscopy (AFM). XPS analysis revealed that the films are oxygen deficient, and XRD analysis with theta-2 theta scans and rocking curves indicate that the ZnO thin films are highly c-axis oriented. All the films are ultraviolet (UV) sensitive. Sensitivity is maximum for the films deposited at lower temperature. The films deposited at higher temperatures show crystallite sizes of typically 500 nm, a high dark current and minimum photoresponse. In all films we observe persistent photoconductivity decay. More densely packed crystallites and a faster decay in photocurrent is observed for films deposited at lower temperature. (C) 2009 Elsevier B. V. All rights reserved.
Original languageUnknown
Pages (from-to)5917-5921
JournalApplied Surface Science
Volume255
Issue number11
DOIs
Publication statusPublished - 1 Jan 2009

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