A MODEL OF THE TEMKIN-ISOTHERM BEHAVIOR FOR HYDROGEN ADSORPTION AT PD-SIO2 INTERFACES

A simple electrostatic model of the adsorbate-adsorbate interaction of hydrogen atoms at a Pd-SiO2 interface is presented. The model predict s a hydrogen adsorption isotherm of the Temkin type. It is found that, in practice, an upper limit for the hydrogen response of a Pd-metal-o xide-semiconductor device exists. The value (in V) is equal to the dif ference of the initial heats of adsorption (in eV) of the interface an d the Pd bulk, respectively. Furthermore, a corresponding maximum hydr ogen concentration, at the interface, of 1x10(18) m(-2) is predicted. The predictions are in good agreement with previously observed experim ental data. (C) 1997 American Institute of Physics.