Amorphous silicon thin films applied to photochemical sensors

The present paper describes the properties of a photochemical sensor based on amorphous silicon MIS (Metal-Insulator-Semiconductor) diodes. The structure of the sensors used in this work are based on glass/Cr/a-SiH(n ⁺)/a-Si:H(i)SiO_x/Pd, where the amorphous silicon layers have been deposited by conventional plasma r.f. techniques. The proposed photochemical sensors present a 2-3 orders of magnitude change in the saturation current and a decrease of up to 40% on the open circuit voltage when in the presence of 400 ppm of hydrogen. The overall performance of these sensors, associated with the low cost fabrication technology, suggests that, in the near future, it will be possible to use them in several industrial applications.