Sensors for detecting molecular hydrogen based on Pd metal alloys

A simple process using a shadow mask is described to fabricate Pd/Ni resistors for detecting H-2. The performance of the resistive sensors is studied in relation to annealing the devices at different temperatures in 2% H-2 in N-2 for 2 h. The Pd/Ni film surface morphology is also examined in relation to the resistor response when exposed to H-2. The detailed information learned about the performance of the prototype resistors is used to fabricate wide-range-hydrogen microsensors, which combine a Pd/Ni chemiresistor and metal-oxide semiconductor capacitor along with a thin film metal heater and temperature sensor. These studies provide an important step for improving the reliability of microsensors used to detect H-2 over concentrations ranging from 1 mTorr to 700 Torr.