On-chip growth of one-dimensional In₂O₃ nanostructures by vapor trapping method and their comparative gas-sensing performance

In this study, we use the chemical vapour deposition trapping method to grow various one-dimensional (1D) indium oxide (In 2 O 3 ) nanostructures, namely nanorods (NRs), nanoneedles (NNs), and nanowires (NWs). The structural and morphological characteristics of the synthesised nanostructures are analysed using x-ray diffraction and scanning electron microscopy. By comparing the morphology of In 2 O 3 under different growth conditions with previous research findings, we investigate the growth mechanism and the role of gold catalysts. The In 2 O 3 sensor presented a good selection for C 2 H 5 OH gas. The NWs-based sensor exhibits a superior response and faster response-recovery rates (50%, and 49 s/343 s) in comparison to the NRs- (45%, and 35 s/339 s) and NNs-based sensors (8%, and 70 s/496 s) when exposed to 200 ppm C 2 H 5 OH at 400 °C. Besides, the sensors exhibited good stability under the switch-off reversible cycle. The linear discriminant analysis (LDA) model was effectively used in classifying target gases such as 25–200 ppm C 2 H 5 OH, NH 3 , and CO at the temperature of 350 °C–450 °C. We attribute the NWs-based sensor’s better gas-sensing performance to its favourable morphology for gas diffusion and modulation of depletion depth.