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Copper Doped ZnO Thin Film for Ultraviolet Photodetector with Enhanced Photosensitivity

Published online by Cambridge University Press:  25 January 2013

Akshta Rajan ,
Kashima Arora ,
Harish Kumar Yadav ,
Vinay Gupta  and
Monika Tomar
Akshta Rajan
Affiliation:
Department of Physics and Astrophysics, University of Delhi, Delhi, INDIA.
Kashima Arora
Affiliation:
Department of Physics and Astrophysics, University of Delhi, Delhi, INDIA.
Harish Kumar Yadav
Affiliation:
Department of Physics, St.Stephens College, University of Delhi, Delhi, INDIA.
Vinay Gupta
Affiliation:
Department of Physics and Astrophysics, University of Delhi, Delhi, INDIA.
Monika Tomar
Affiliation:
Physics Department, Miranda house, University of Delhi, Delhi, INDIA.
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Abstract

Ultraviolet photoconductivity in Copper doped ZnO (Cu:ZnO) thin films synthesized by sol-gel technique is investigated. Response characteristics of Pure ZnO thin film and Cu:ZnO thin film UV photodetector with 1.3 at. wt % Cu doping biased at 5 V for UV radiation of λ = 365 nm and intensity = 24 µwatt/cm2 has been studied. Cu:ZnO UV photodetector is found to exhibit a high photocoductive gain (K = 1.5×104) with fast recovery (T90% = 23s) in comparison to pure ZnO thin film based photodetector (K = 4.9×101 and T90% = 41s). Cu2+ ions have been substituted in ZnO lattice which has been confirmed by X-ray diffraction (XRD) and Raman spectroscopy leading to lowering of dark current (Ioff ∼ 1.44 nA). Upon UV illumination, more electron hole pairs are generated in the photodetector due to the high porosity and roughness of the surface of the film which favours adsorption of more oxygen on the surface of the photodetector. The photogenerated holes recombined with the trapped electrons, increasing the concentration of photogenerated electrons in the conduction band enhancing the photocurrent (Ion ∼ 0.02 mA) of the Cu:ZnO photodetector.

Keywords

photoconductivitysol-gelthin film
Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 1494: Symposium Z – Oxide Semiconductors and Thin Films , 2013 , pp. 43 - 49
Copyright
Copyright © Materials Research Society 2013 

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References

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