Photoluminescence and photoconductivity studies of ZnO nanoparticles prepared by solid state reaction method
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In the present work, the effect of annealing temperature on the luminescence and photoconductivity properties of ZnO nanoparticles (NPs) has been investigated. The ZnO NPs have been prepared at low temperature by a simple one step solid state reaction method using ZnSO4·7H2O as a starting precursor. X-ray diffraction results show, the prepared samples have a hexagonal wurtzite structure of ZnO NPs. FE-SEM reveals that the prepared ZnO nanoparticles have perfect spherical shape with little agglomeration. UV–visible absorption spectrum of as-prepared ZnO sample shows an absorbance peak at ~372 nm (~3.32 eV), which is blue shifted as compared to bulk ZnO (~386 nm). The annealed sample exhibits red shift of absorption peak. The photoluminescence spectra of as-prepared sample as well as annealed samples show one emission peak in UV region, and violet, blue, blue-green and green emissions in visible region. The sample annealed at 650 °C results in a significant reduction in luminescence as compared to that of the sample annealed at 450 °C. The photoconductivity properties such as voltage dependence of photocurrent, growth and decay of photocurrent as well as wavelength dependence of photocurrent have been studied in detail.
KeywordsSolid State Reaction Method Visible Emission Trap Depth Space Charge Limited Current Photoconductivity Property
One of the authors, Dr. Rajneesh K Srivastava, is thankful to UGC for its support in form of a project grant (No. 37-395/2009 (SR)). The authors are also thankful to Prof. A. C. Pandey for providing XRD and PL measurements at Nanotechnology Application Centre, University of Allahabad. We are also thankful to Saha Institute of Nuclear Physics (SINP), Kolkata for SEM characterization facility. Dr. Sheo K. Mishra is grateful to SINP, Kolkata for providing financial assistance under Postdoctoral Fellowship during the analysis and revision of this work.
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