Potential of Porous Silicon Machined by Laser Photoetching to be used as Sensor

In this work, the capacity of porous silicon (PS) machined by laser photoetching was studied as an ethanol sensor, as well as the influences of the type and the conductivity of the crystalline silicon used to obtain sensors. The resistivities used were 1–10 and 0.0014–0.004 Ω∙cm, both wafers were n-type. The response of the device was determined at room temperature (27 °C). The results can be used to appropriately select the conductivity of semiconductor materials to be used as sensors. Infrared spectroscopy confirms the absorption of ethanol in the surface of the photoetched PS. Morphological analysis revealed a macroporous structure, with pore diameters of 2.6 and 0.39 μm for the wafers of 1–10 and 0.0014–0.004 Ω∙cm respectively. The macroporous structure demonstrates a high sensibility and exhibited excellent sensing characteristics during the detection of low concentrations of ethanol. The quantity of ethanol was registered with the changes in the voltage of operation. The performance of the sensor was characterized by curves of voltage vs. time. The minimum quantity of ethanol analyzed was 1 µl. The results demonstrate that photoetched PS has the potential to develop sensitive sensors.