Fabrication and characterization of CuO/CdS heterostructure for optoelectronic applications
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ORIGINAL PAPER: DEVICES BASED ON SOL-GEL OR HYBRID MATERIALS
Fabrication and characterization of CuO/CdS heterostructure for optoelectronic applications A. Kathalingam
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K. Kesavan2 V. Mary Pradeepa2 Hyun-Seok Kim3 ●
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Received: 10 April 2020 / Accepted: 14 August 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract This paper reports the fabrication of a CuO/CdS heterostructure and the characterization of its properties for optical sensing. Cadmium sulfide (CdS) and cupric oxide (CuO) films were deposited by spray pyrolysis and hydrothermal techniques in order to fabricate CuO/CdS heterojunction devices. The structural, morphological, and optical properties of the CuO and CdS thin films were analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and UV–vis spectroscopy. The concentration of the sulfur precursor, thiourea, was varied over a range from 0.01 to 0.06 M in the spray coating solution for CdS films, and 0.05 M was found to yield improved structural and optical properties. The prepared p-CuO/n-CdS heterojunction exhibited good optical sensing properties with excellent response and recovery speeds. A possible photosensing mechanism for the fabricated heterostructure is detailed using energy band diagrams. In addition, heterojunction properties, including the ideality factor and conduction mechanism are reported: a fabricated heterostructure diode showed a threshold voltage of 0.036 V and an ideality factor of 1.86. Graphical Abstract
Keywords
CuO/CdS heterojunction Photodiode Photosensor Hydrothermal method Spray pyrolysis technique ●
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* Hyun-Seok Kim [email protected]
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Department of Physics, Periyar Maniammai Institute of Science and Technology, Valam, Thanjavur 613 403, India
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Division of Electronics and Electrical Engineering, Dongguk University-Seoul, Seoul 04620, Republic of Korea
Millimeter-Wave Innovation Technology Research Center (MINT), Dongguk University-Seoul, Seoul 04620, Republic of Korea
Journal of Sol-Gel Science and Technology
Highlights ● p-CuO/n-CdS heterojunction photodiode is fabricated using hydrothermal and spray pyrolysis methods. ● Sulphur concentration of 0.05 M shows excellent structural and optical properties of CdS film. ● Fabricated heterojunction ideality factor is 1.86 and I-V nature indicated formation of diode. ● The photodiode showed fast recovery and response times for visible light sensing.
1 Introduction In this era of quickly developing technology, photosensing is widely used in military, medical and other applications. In particular, CuO/CdS heterojunctions can be used in photosensing and photovoltaic devices, the latter of which addresses growing global energy demands. Metal chalcogenide materials such as PbS, ZnS, CdS, CdSe, PbSe, ZnSe, and ZnTe have attractive properties for various optoelectronic applications. Among these, CdS is attractive for photosensing applications in the visible region because of its bandgap energy of 2.4 eV
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