A chemiresistive carbon monoxide (CO) gas sensor comprising of an organo-di-benzoic acidified zinc oxide (ODBA-ZnO) nanohybrid material is reported. The ODBA-ZnO hybrid material is prepared via a single-pot hydrothermal method. The electrical resistance of the drop-casted ODBA-ZnO film on interdigitated electrodes increases noticeably upon exposure to CO (5−500 ppm). The resistance increase is attributed to the formation of complex ions at the organic (ODBA)−inorganic (ZnO) interface in the presence of CO. The detailed CO sensing properties of the ODBA-ZnO nanohybrids reveal a remarkable selectivity to CO gas in comparison to other gases like CO 2 , H 2 S, and NH 3 at 125 °C. The maximum response to 100 ppm of CO is observed to be 35% with the achieved selectivity to CO being 88%, which is the best reported CO selectivity result available in the literature to date. The ODBA-ZnO nanohybrid sensor takes nearly 91 s to reach the saturated response to 100 ppm of CO and nearly 175 s to recover from it in a synthetic air environment. A systematic study using field emission scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, nitrogen adsorption−desorption tests, and thermogravimetric analysis reveals that introduction of an organic moiety (ODBA) to ZnO played a key role in achieving improved selectivity and sensitivity toward CO. The present work provides a simple route for fabricating the ODBA-ZnO sensor to achieve better selectivity and sensitivity to CO gas at a relatively low temperature (125 °C).
Here, we present an analytical modeling of electron mobility in two dimensional electron gas (2DEG)-yielding MgZnO/ZnO heterostructures, to ascertain dominant scattering mechanisms and physical parameters responsible for one-order lower value of electron mobility in sputtering-grown heterostructure as compared to that in molecular beam epitaxy-grown heterostructure. This work extensively probes all scattering components and their physical parameters, such as dislocation density, impurity density, mole fraction, 2DEG density, correlation length and lateral size, for their respective effects on electron mobility of sputtered heterostructure. The results suggest that dislocation density and alloy disorder scattering are the most dominant sources responsible for reduced electron mobility. This work is extremely crucial for achieving high electron mobility by optimizing the material growth parameters to attain low dislocation density, impurity density and interface roughness, for the development of low-cost ZnO-based heterostructure field effect transistors.
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