Abstract
An NH3 gas sensor was prepared from nanocomposite films of indium oxide-copper oxide mixtures with ratios of 0 , 10 , and 20 Vol % of copper oxide. The films were deposited on a glass substrate using chemical spray pyrolysis method (CSP) at 400oC. The structural properties were studied by using X-ray diffraction (XRD) and atomic force microscopy ( AFM). The structural results showed that the prepared thin films are polycrystalline, with nano grain size. By mixing copper oxide with indium oxide, the grain size of the prepared thin films was decreased and the surface roughness was increased. The UV-Visible spectrometer analysis showed that the prepared thin films have high transmittance. This transmittance was decreased by mixing copper oxide with indium oxide. The direct optical energy gap ranged 3.5 - 3 eV, which was decreased with increasing copper oxide concentration. The sensitivity of the prepared gas sensor was measured towards NH3 gas at a concentration of 71ppm with operating temperatures of 100, 150, 200, 250 and 30) oC, according to the change of sensor resistance. This sensitivity of the mixture oxides showed a value of about nine times greater than that of individual indium oxide thin films. The results of the optimum gas sensor properties demonstrated a sensitivity value of 75.06%, response time of 10s, and recovery time of 11 s, at a mixing ratio of 20% of copper oxide and an operating temperature of 200oC.
Highlights
Semiconductor metal oxide (SMO) has many advantages, such as low cost, easy for fabrication, low detection limits for gases, in addition to their long life, non-toxicity, and high conductivity
The present study was designed to manufacture an NH3 sensor from nanocomposite thin films made of a mixture of indium oxide and copper oxide deposited on a glass substrate by a simple chemical spray pyrolysis technique
It was found that the addition of copper oxide leads to a decrease in the crystal size as compared with individual indium oxide thin film, as shown in Table-1
Summary
Semiconductor metal oxide (SMO) has many advantages, such as low cost, easy for fabrication, low detection limits for gases, in addition to their long life, non-toxicity, and high conductivity. For these properties, it has been used in many different fields and applications, such as solar cells and gas sensors [1]. Indium oxide (In2O3) is an n-type semiconductor with a wide energy gap n (3.5- 3.75 eV) It has high conductivity, low resistance, and ability to modify its surface by doping or mixing with some metals [10]. The structural, optical, and sensing properties of 71 ppm NH3 gas of the prepared films were studied
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