Hydrothermally Synthesized ZnSe Nanoparticles for Relative Humidity Sensing Application
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https://doi.org/10.1007/s11664-020-08320-6 2020 The Minerals, Metals & Materials Society
Hydrothermally Synthesized ZnSe Nanoparticles for Relative Humidity Sensing Application UPASANA CHOUDHARI1 and SHWETA JAGTAP1,2 1.—Department of Instrumentation Science, Savitribai Phule Ganeshkhind, Pune 411007, India. 2.—e-mail: [email protected]
Pune
University,
This paper describes hydrothermally synthesized ZnSe nanoparticles for resistive-type relative humidity sensors. The structural, optical and morphological characterization of synthesized ZnSe nanoparticles was analyzed by means of x-ray diffraction, UV–vis spectroscopy, Fourier transform infrared spectroscopy, photoluminescence and transmission electron microscopy. Also, the details of the fabrication process and humidity sensing mechanism are described. The considerable sensitivity, response and recovery time is achieved due to enhanced electron transfer capability of ZnSe nanoparticles. The film resistance changes with relative humidity (RH) for approximately three orders of magnitude (109–106) over the range of 20–100% RH shows reasonably good sensitivity. This indicates the promising applications of ZnSe nanoparticles for room temperature environmental monitoring. Further, the response and recovery time, repeatability and reproducibility of the humidity sensors are also measured. Key words: Zinc Selenide nanoparticles, resistive humidity sensors, Cole–Cole plot, I–V characteristics
INTRODUCTION The nanostructured materials with a defined size and shape have attracted much interest in fundamental research for electronic and optoelectronic nano-devices.1 The Zn based II–VI semiconductors such as zinc selenide (ZnSe) has wide direct band gap (2.67 eV) and large exciton binding energy (21 meV), and hence ZnSe is most popularly considered for optoelectronic devices.2,3 Typically, ZnSe has a zinc blende structure (with lattice constant = 5.667 A), but can also exist in a metastable wurtzite form. Recently, a variety of various dimensional ZnSe nanostructured materials have been reported, such as nanoparticles,4 nanoroads,5 nanowires,6 nanobelts,7 nanoneedles,8 nanotubes 9 and nanoplates.10 Several ZnSe synthesis routes are being reported, such as hydrothermal,11 solvothermal,12 metalorganic vapor phase
(Received March 13, 2020; accepted July 8, 2020)
deposition,13 modified vapor deposition,14 simple thermal evaporation,15 chemical vapor deposition,16 low-temperature,10 reverse micelle synthesis,17 and microwave-irradiation.18 Among various methods, hydrothermal technique has several advantages such as use of simple equipment, high purity, narrow particle size distributions, catalyst-free growth, fast reaction time, low cost, and it is ecofriendly and less hazardous.19 In the twenty-first century hydrothermal technology also has offered a new perspective in fields such as geotechnology, nanotechnology, biotechnology and some advanced materials technology.20 ZnSe has attracted intense attention in recent years because of the potential applications in vari
