Development of Ethanol Sensor Based on Vertically Aligned SnO2/TiO2 Heterojunction Nanowire Using GLAD Technique

This study investigates the fabrication of a vertically aligned TiO2/SnO2 heterojunction nanowire (NW) using e-beam evaporation with glancing angle deposition (GLAD). The sensing properties of the fabricated device were tested with different ppm of ethanol and acetone. The device demonstrated a significant response (S) of ~3.2 at concentrations of 200 ppm of ethanol at
$150~^{\circ }$
C with the corresponding response and recovery times of ~41 and ~84 s, respectively, at +3-V bias. The recorded values of current at +3 V are ~0.1 and ~0.8 mA for ambient conditions and ethanol (under 200 ppm), respectively. It is interesting to observe the sensing performance of the metal-oxide-semiconductor (MOS) heterojunction NW-based gas sensor, which can be attributed to the synergistic effect and large surface-to-volume ratio of vertically aligned TiO2/SnO2 heterostructure NWs that enhances the absorption and desorption processes. This study marks the first time report on a GLAD-based SnO2-NW/TiO2-NW heterostructure gas sensor, showcasing its potential for practical applications in environmental monitoring and gas sensing technologies.