Synthesis of SnO 2 Nanowires on Quartz and Silicon Substrates for Gas Sensors
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Synthesis of SnO2 Nanowires on Quartz and Silicon Substrates for Gas Sensors Khalef Wafaa Khalid1 · Aljubouri Ali Abadi1 · Faisal Abdulqader Dawood1 Received: 18 November 2019 / Accepted: 24 May 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Tin oxide nanowires ( SnO2 NWs) were grown on quartz and silicon substrates via a modified chemical vapor deposition (CVD). Film of gold nanoparticle deposited on both types of substrates using the direct current DC-sputtering technique. The structure and morphology of the produced material were characterized by using atomic force microscopy, X-ray diffraction (XRD), scanning electron microscope (SEM) and ultraviolet–visible (UV–Vis) techniques. The XRD and SEM analysis confirmed the formation of tetragonal S nO2 NWs with a wire length of 10–20 μm and a diameter of 40–100 nm. The UV–Vis spectrum shows a strong absorption peak in the UV and others in the visible regions. The bandgap was calculated for SnO2 NWs grown on a quartz substrate within the value of 3.2 eV. It is slightly lower than the bandgap value of bulk. The successfully synthesized S nO2 NWs via CVD with a large aspect ratio in the range of 250–200 was proved to be quite promising nanomaterials to use for sensor fabrication towards ethanol gas at room temperature. The high sensitivity of 2.7 at an ethanol gas concentration of 500 parts per million (ppm) was achieved. The proposed sensing mechanism of SnO2 NWs towards ethanol gas was also discussed. Keywords Tin oxide nanowires · Band gap · Activation energy · Ethanol gas sensors
1 Introduction Tin dioxide (SnO2) is an n-type semiconductor that has a wide bandgap (3.6 eV at 300 K) so that it can be used in a variety of technologies [1, 2]. SnO2 is used in electrochemical energy storage [3], catalysts [4], and gas sensors [5, 6]. The gas-sensing behaviors of semiconductor materials directly depend on their preparation methods and conditions. The large ratio of surface to volume must be achieved to ensure high sensitivity. The good performance of the sensors can be achieved by minimizing the size of the particles [7]. One of the main objectives of the researches in gas sensing is the obtaining of nanostructures of various morphologies with decreasing of the dimension, which affects the surface [8–11]. Many efforts have been made to improve the sensitivity of S nO 2, including modifying its morphology. For instance, some morphologies that have been obtained are * Aljubouri Ali Abadi [email protected] 1
nanostructures such as, nanowires [12] and nanosheets [13]. There is no relatively much work has been done related to the room temperature gas sensor based on as-synthesized SnO2 NWs. A variety of techniques have been used to synthesize tin oxide nanostructures. These include chemical vapor deposition (CVD) [14], vapor transport [15], carbothermal reduction [16], laser ablation [17], hydrothermal synthesis [18], sol–gel [19] and electrospinning [20]. The present study represents the synthesis of SnO2 NWs
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