Optical and sensing properties of sputtered indium tin oxide (ITO) thin films

Abstract

Two sets of indium tin oxide thin film were prepared at different thicknesses onto the corning glass substrates using radio frequency magnetron sputtering method. Set one is for single configuration sample and set two is for sensor array sample. All samples were annealed at temperature of 600°C for 4 hours inside a furnace. A surface profiler was used to measure the thickness of the samples while a UV-VIS spectrophotometer was used to measure their optical properties. The gas sensing characterization system was used to determine the gas sensing properties in 200 ppm of nitrogen dioxide, NO2. The thickness of the sample was found to be in the range of 132 nm to 424 nm. The transmittance and the optical band gap decrease as thickness increases. The resistance decreased to several kilo ohms when the operating temperature increased for all samples. The highest sensitivity for single configuration was found in sample C with thickness 227 nm (45 minutes deposition time). Sample H has the highest sensitivity (combination of 15 minutes + 90 minutes deposition times) for array configuration. Thus, the response time and the corresponding recovery time for sample C were 66.6 seconds and 133.2 seconds respectively; while for sample H, the response time was 60 seconds and recovery time was 333.6 seconds.