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.