Development of Silver Doped Titanium Oxide Thin films for Gas Sensor Applications

Abstract

Gas sensors find numerous applications in fields of automotives, medical, industries and others. A number of studies focused on synthesis of silver doped titanium dioxide films with various doping concentrations of silver. The objective of the research work is to optimize gas sensing properties of Ag-TiO2 thin films using orthogonal array experimentation with different dopants, concentration, annealing temperatures and gas concentrations exposure time. Synthesis of Ag-TiO2 thin films on quartz substrates was carried out by sol-gel spin coating. TiO2 films were characterized optical, chemical and mechanical and sensing properties. Surface roughness of TiO2 Thin films are RSM 11 to 45 nm and decrease of transmittance from 74% to 45% and energy bad gap from 3.44 to 3.29 eV for variation of annealing temperature from 400 to 600 °C. Surface roughness in RSM of 15 to 67 nm and decrease in transmittance from 85 to 63 % and band gap from 3.40 to 3.28 eV from 3 to 7 layers of coating was found. Ag-TiO2 thin films showed highest sensor response of 1.247 for 300 °C annealing temperature, 0.025 atomic ratio, 5 ppm CO gas exposure. Analysis of variance showed CO gas exposure influenced sensor response by 72.95%, and annealing temperature influenced sensor response by 18.39 %. Response surface methodology showed desirability of 70.7% with maximum response value to be 1.2346.