Organic vapour sensing by current response of porous silicon layer

In this paper, a porous silicon (PS) layer is investigated as a sensing material to detect organic vapours with low concentration. To do this PS sensors with membrane structure were designed and fabricated. The sensors were made by applying the technologies of membrane formation by anisotropic etching of silicon and PS formation by anodization in HF solution. From fabricated sensors, current-voltage (I-V) curves were measured for ethanol (called alcohol), methanol and acetone gases evaporated from 0.1-0.5% solution concentrations at 36degreesC. As a result, all curves showed rectifying behaviour due to a diode structure between Si and the PS layer. The conductance of our sensors mostly increased along with the organic solution concentration at a high voltage of 5 V, but the built-in potential on the measured I-V curve was lowered with it by the adsorption effect of the organic vapours with high dipole moment.