Hydrogen sensors based on metal-insulator-semiconductor structures with a layer of a proton-conducting solid electrolyte

Application of solid electrolytes as undergate layers accelerates the response of a sensor at room temperature as compared with ordinary hydrogen sensors manufactured on the basis of the metal-insulator-semiconductor (MIS) structures with a palladium gate. The proton-conducting solid electrolytes under study include NAFION, zirconium hydrophosphate, and etherified polyvinyl alcohol (PVA) with heteropolyacids and phenoldisulfonic acid, which can be deposited under the platinum gate. Sensors based on the MIS structures with these solid electrolytes show a high sensitivity toward hydrogen (similar to 120 mV per concentration decade). The response time tau(0.63) of a freshly manufactured sensor with a layer of zirconium hydrophosphate amounts to about 2 min. The maximum mechanical stability, especially at relative humidities in excess of 80% is intrinsic to sensors containing layers of PVA with heteropolyacids. The response time of such sensors is nearly 10 min.