Plasma-induced sub-10 nm Au-SnO2-In2O3 heterostructures fabricated by atomic layer deposition for highly sensitive ethanol detection on ppm level

Abstract Two-dimensional (2D) Au-SnO2-In2O3 heterostructures with thickness less than 10.0 nm were fabricated on 4-inch Si/SiO2 wafers by the plasma-enhanced atomic layer deposition (PE-ALD) technique as functional electrodes for electrochemical ethanol sensors. Structural, morphological and electrochemical characteristics of the developed 2D samples were subsequently characterized by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), Atomic Force Microscopy (AFM), Raman spectroscopy and Fourier transform infra-red spectroscopy (FTIR). The sensing properties of the 2D heterostructures were evaluated at the different temperatures, ethanol concentrations and at the presence of other gases. The optimum working temperature of 350 °C for 2D Au-SnO2-In2O3 was established. Plasma-induced Au-SnO2-In2O3 heterostructures demonstrated fast response/recovery times (5.0 s/33.0 s), one of the highest changes in resistivity to ethanol, low limit of detection (LOD) (1.0 ppm), great selectivity and long-term stability compared to other SnO2- and In2O3-based sensing electrodes reported to date. Developed PE-ALD recipe for 2D heterostructured electrodes enables sensors’ miniaturization and batch-to-batch reliability during their mass fabrication.