Hydrogen sensitive negative switching behavior in metal-oxide-semiconductor devices

Hydrogen sensitive switching device with a Pd-thin SiO2-(n)Si-(p(+))Si stru cture which has thyristor-like S-shape property and of which threshold volt age was sensitive to hydrogen concentration was studied by using an impedan ce measurement for the first time. The switching device was considered to b e a series connection of MIS junction and p(+)n junction. Four equivalent c ircuit parameters of two parallel connections of a capacitance and a resist ance corresponding to two junctions were estimated under several bias and h ydrogen conditions. Dependence of the parameters on bias voltage and on amb ient hydrogen concentration is shown. The properties of these parameters re veal the behavior of MIS and p(+)n junction and their mutual interaction. A hydrogen sensitive switching mechanism is discussed. The impedance method is available to clarify the operation mechanism of the switching device. (C ) 2001 Elsevier Science B.V. All rights reserved.