A CAPACITANCE TYPE CHEMICAL SENSOR-BASED ON ALPO4-5 MOLECULAR-SIEVES

Thin films of AlPO4-5 molecular sieves have been employed as the diele ctric phase in a capacitance type chemical sensor. AlPO4-5 was deposit ed onto titanium nitride (bottom electrode) coated silicon wafers by l aser ablation. A subsequent hydrothermal treatment-of the ablated AlPO 4-5 films was found to enhance the crystallinity. The capacitance sens or configuration was completed by the deposition of Pd/Au pads (upper electrode) through a mask. AlPO4-5 based sensors exhibited significant changes in capacitance upon exposure to small molecules such as CO2, CO, N-2, and H2O.