Development of Ethanol Sensor Based on Vertically Aligned SnO$_{\text{2}}$/TiOTEXPRESERVE1 Heterojunction Nanowire Using GLAD Technique

This study investigates the fabrication of a vertically aligned TiO $_{\text{2}}$ /SnO $_{\text{2}}$ 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 ( $\textit{S}$ ) of $\sim$ 3.2 at concentrations of 200 ppm of ethanol at 150 $^{\circ}$ C with the corresponding response and recovery times of $\sim$ 41 and $\sim$ 84 s, respectively, at $+$ 3-V bias. The recorded values of current at $+$ 3 V are $\sim$ 0.1 and $\sim$ 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 TiO $_{\text{2}}$ /SnO $_{\text{2}}$ heterostructure NWs that enhances the absorption and desorption processes. This study marks the first time report on a GLAD-based SnO $_{\text{2}}$ -NW/TiO $_{\text{2}}$ -NW heterostructure gas sensor, showcasing its potential for practical applications in environmental monitoring and gas sensing technologies.