Catalyst free vapor-solid deposition of morphologically different β-Ga2O3 nanostructure thin films for selective CO gas sensors at low temperature

In the present work, we have demonstrated the deposition of novel morphologically different beta-Ga2O3 nanostructure (rod and rectangular shape) thin films prepared by a vapour solid mechanism using a temperature controllable horizontal tubular furnace without using any metal catalyst or additives. The effects of growth parameter, surface morphology and particle size on the beta-Ga2O3 thin films were systematically investigated using electron micrograph images. X-ray diffraction patterns of the prepared films reveal preferential orientation along the (111) plane. In addition, studies of the toxic carbon monoxide (CO) gas sensing performance show that the as-prepared rod shaped beta-Ga2O3 nanostructures show good sensitivity, short response and recovery time (49-40 s) upon exposure to CO gas at 100 degrees C in comparison with rectangular shape beta-Ga2O3 (56-63 s). Through exploring the gas sensing mechanism, it is argued that the sensor performance dramatically improves due to the high surface area, particle size, shape, numerous surface active sites and the oxygen vacancies. The developed 1D beta-Ga2O3 thin films not only possess unique shape and size, but also influence the development of various potential applications.