Optimizing Sensitivity of Room Temperature CO2 Sensors through Co-Doped ZnO Nanorods By Magnetron Sputtering System

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Metal oxide semiconductors (MOS) based gas sensors have been identified as a promising solution for future applications due to their exceptional electrochemical, physical, and gas sensing properties. Due to their excellent optical and electrical features, ZnO nanostructures have become increasingly popular for gas detection applications, mainly because of their abundant availability. Despite its potential, the ZnO-based sensors have challenges such as poor selectivity and high power consumption at elevated operating temperatures. Transition metal doping, for example with cobalt depicted decent promising results in high response and selectivity of ZnO nanomaterials towards certain gasses. This study investigates the sensitivity enhancement of room temperature CO2 sensors utilizing the cobalt-doped ZnO (CZO) nanorod architecture. The CZO thin films were deposited on glass substrates using radio frequency (RF) magnetron sputtering at varying powers. Structural, morphological, and gas response properties of the CZO thin films were analyzed.Figure 1 illustrates the evolution of resistance over time for CZO sensors when exposed to CO2 gas concentrations ranging from 1 to 500 ppm at room temperature in dry air. In this investigation, the response to gas follows a consistent linear pattern within the 1−300 ppm range. However, as the concentration rises, a noticeable deviation towards nonlinearity becomes more pronounced. The sensor exhibits a heightened response across various concentration levels: 1 (8.9), 50 (12.5), 100 (14.79), 150 (15.7), 250 (18.82), and 500 (23.52) ppm. Discrepancies in the sensor response are attributed to the distinct surface morphology inherent to each sensor type. The introduction of co-doping enhances the occurrence of point defects and oxygen vacancies within the CZO sensors. The Scanning Electron Microscopy (SEM) images reveal that the CZO material exhibits a highly organized surface morphology, characterized by densely packed spherical structures, and the cross-sectional analysis of the material shows a uniform thickness of 136 nm, indicating its potential applications in the field of sensing and detection, shown in figure 2. This study underscores the effectiveness of CZO nanorod architecture in rapidly detecting CO2 at room temperature, presenting promising avenues for environmental monitoring and sensing applications Figure 1