Work function gas sensors are normally operating on the principle of potent
ial difference measurements.
In this work, the change of the work function (Delta Phi) of the Pt (< 1 nm
)/Cu layer structure was studied in function of the sample's heat treatment
temperature (23-300 degrees C) in response of 2000 ppm CO using a Kelvin p
robe with a gold grid reference electrode. The aim of the heat treatment wa
s the forming of the "proper size" Pt clusters by Pt diffusion. It was stud
ied by XPS analysis.
In each case it was found that the introduction of the CO decreases the wor
k function by 6-55 mV at room temperature. The optimal heat treatment condi
tions were determined, as 200 degrees C, 1 h, when the change of the work f
unction was 9 mV beside 17 s response and recovery times. (C) 2000 Elsevier
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