On the Creation of Molybdenum-Oxide-Based Layers for Semiconductor Gas Sensors

When developing gas sensors, selecting a suitable gas-sensing material is of great importance. Currently, there is great interest in the development of new gas-sensitive layers based on molybdenum oxide MoO₃ and improvement of their sensor characteristics. In the work, a MoO₃ gas-sensitive layer is obtained by the hydrothermal method followed by annealing at a temperature of 400°C for 2 hours. The elemental composition of the surface of the obtained sample is analyzed using X-ray photoelectron spectroscopy. Studies of the sensor response, response time, and recovery time of the gas-sensitive layer to isopropyl-alcohol vapors at different operating temperatures are carried out. The chemical composition is shown to be consistent with MoO₃, but adsorbed hydroxyl groups are also observed on the surface. Analysis of the sensor properties shows that the sensitivity at temperatures of 250°C and 150°C is 13.3 and 5.5, respectively. It is found that layers based on MoO₃ nanoparticles synthesized by the hydrothermal method exhibit sensitivity to isopropyl-alcohol vapors even at a temperature of 150°C.