INFLUENCE OF CHEMICAL-COMPOSITION ON SENSITIVITY AND SIGNAL REPRODUCIBILITY OF CDS SENSORS OF OXYGEN

It is well known that due to the high sensitivity of CdS to oxygen che misorption, thin films of this semiconductor can be used as oxygen sen sors. In this work CdS sensors are produced by an electrohydrodynamic spray of liquid onto glass substrates heated up to the equilibrium tem perature of the deposition process. Three types of CdS film with diffe rent ratios of initial solvent components have been investigated: Cd:S =(a) 10 (b) 1.0 and (c) 0.1. It is established from XPS quantification that the Cd:S ratio is increased in the film produced from an initial solution with higher Cd:S ratio. Simultaneously the total amount of o xygen on the sensor surface is increased. The obtained experimental da ta demonstrate that an elevation of oxygen concentration is caused by chemisorption, i.e., the chemisorption sensitivity is increased in the case of higher Cd:S ratios.