Ultra-thin sub-10 nm Ga2O3-WO3 heterostructures developed by atomic layer deposition for sensitive and selective C2H5OH detection on ppm level

Wafer-scale ultra-thin WO3 nanofilms, Ga2O3 nanofilms and Ga2O3-WO3 heterostructures with thickness of approximately (similar to)8.0 nm were fabricated on the SiO2/Si substrates by atomic layer deposition (ALD) technique for their subsequent usage as sensing materials for the ethanol detection. Structure and morphology of the developed ultra-thin samples were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, etc. Sensing properties of the developed ultra-thin nanostructures were investigated at the different temperatures and ethanol concentrations. The results showed that Ga2O3-WO3 heterostructures based gas sensor exhibited about 4 and 10-fold improvement in the response to ethanol compared to that of WO3 and Ga2O3 nanofilms at 275 degrees C. Furthermore, the sensor based on Ga2O3-WO3 heterostructures exhibited shorter response/recover time and excellent selectivity towards ethanol. ALD fabrication method provides a great potential for improvement of the sensing capabilities of high-performance gas sensor based on Ga2O3-WO3 heterostructures.