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Fizika Tverdogo Tela, 2021 Volume 63, Issue 3, Page 375 (Mi ftt10155)

This article is cited in 6 papers

Semiconductors

Surface modification of ZnO nanowires with CuO: a tool to realize highly-sensitive H$_2$S sensor

C. P. Goyalabc, D. Goyala, N. S. Ramgird, M. Navaneethana, Y. Hayakawac, C. Muthamizhchelvana, H. Ikedabc, S. Ponnusamya

a Functional Materials and Energy Devices Laboratory, Department of Physics and Nanotechnology, SRM IST, Kattankulathur, Tamil Nadu 603 203, India
b Graduate School of Science and Technology, Shizuoka University
c Research Institute of Electronics, Shizuoka University, Hamamatsu 432 8011, Japan
d Technical Physics Division, Bhabha Atomic Research Center, Mumbai 400 085, India

Abstract: Hydrothermally grown ZnO nanowires (NWs) have been successfully synthesized and surface modified by an ultrathin layer of CuO using dip coating technique to achieve a highly sensitive H$_2$S sensor. XRD analysis confirmed the hexagonal structure of ZnO without any Cu sub-oxide peaks. After CuO modification, the peak shift was observed in the electronic states of O and assigned to the defects and increase in adsorbed oxygen species. Similarly, a red shift was also observed in the band edge absorption after CuO modification arising due to defects. The sensor film showed an overall $n$-type character as confirmed using I(V) characteristics. Interestingly, sensor response kinetics towards H$_2$S were enhanced after CuO modification. The highest sensor response value of 298 was measured towards 10 ppm H$_2$S at 150$^\circ$C for CuO : ZnO NWs sample having 1.26 at.% of Cu. This improved sensor response has been attributed mainly to the formation of randomly distributed $p$$n$ nano-hetero-junctions between $p$-type CuO and $n$-type ZnO over the sensor surface. In particular, the $p$$n$ nano-hetero-junctions collapsed due to conversion of semiconducting CuO into metallic CuS after the unique interaction with H$_2$S.

Keywords: ZnO nanowires, gas sensing, H$_2$S, surface modifications, $p$$n$ hetero-junctions.

Received: 29.10.2020
Revised: 29.10.2020
Accepted: 03.11.2020

Language: English


 English version:
Physics of the Solid State, 2021, 63:3, 460–467


© Steklov Math. Inst. of RAS, 2024