Examination of the CO/Pt/Cu layer structure with Kelvin probe and XPS analysis

Work function gas sensors are normally operating on the principle of potential difference measurements. s work, the change of the work function (ΔΦ) of the Pt (<1 nm)/Cu layer structure was studied in function of the sampleʹs heat treatment temperature (23–300°C) in response of 2000 ppm CO using a Kelvin probe with a gold grid reference electrode. The aim of the heat treatment was the forming of the “proper size” Pt clusters by Pt diffusion. It was studied by XPS analysis. h case it was found that the introduction of the CO decreases the work function by 6–55 mV at room temperature. The optimal heat treatment conditions were determined, as 200°C, 1 h, when the change of the work function was 9 mV beside 17 s response and recovery times.