Comparison and influence of metal dopants on the opto-electrical, microstructure and gas sensing properties of nanostructured indium oxide films

Abstract

Thin films of pure and Sn, Zn, Mn, and Ag-doped indium oxide (In2O3) with a thickness of 150 nm are grown by co-deposition using thermal evaporation technique and annealed at 500 °C. The crystal lattice strain, dislocation density, optical band gap, surface roughness, and gas sensitivity of the films are studied. Comparison of AFM results shows that the Ag-doped In2O3 has the highest roughness. The ethanol vapor sensing results demonstrate that 3% Ag-doped In2O3 films have higher sensitivity at the operating temperature of 325 °C to 1000 ppm of ethanol vapor, due to the presence of more roughness and defects than other films. The response and recovery times of this sample at 1000 ppm ethanol vapor were 32 and 51 s, respectively. Finally, it is shown how 3% of metal impurities in the In2O3 layer can affect the optical, microstructural, and gas sensing parameters of the samples, and also investigated the correlation between them.