Organic analytes sensitivity in meso-porous silicon electrical sensor with front side and backside contacts

Publication date: Available online 26 May 2017 Source:Arabian Journal of Chemistry Author(s): F.A. Harraz, A.A. Ismail, M. Faisal, S.A. Al-Sayari, A. Al-Hajry, M.S. Al-Assiri Chemical sensors fabricated from porous silicon (PSi) for liquid organic analytes (ethanol, acetonitrile, methanol, acetone) are demonstrated, with an emphasis on the impact of the Ag electrical contact placement on sensor performance. Sensors with front side contact display larger shift in capacitance response (2-3 times more sensitive) compared to the backside sensor design as the solvents immediately interact with the pore openings before infiltration. Much slower response time (7 to 30 minutes range) for front side vs. (50 to 200 seconds scale range) for backside configuration is observed. Both sensor designs exhibit excellent solvent infiltration-evaporation reversible response, indicating no chemical reaction or surface modification occurred. The response time was in the order of ethanol > acetonitrile > methanol > acetone, which correlates well with the solvent vapor pressure. The capacitance shift in both sensor devices is likely related to the interface interaction, revealing a closer correlation with the dipole moments of solvents. This is supported by the photoluminescence quenching upon exposure to organic solvents, with a relative intensity decrease tracks with the dipole moment. The sensitivity remains sufficiently high during the repeated use, with excellent st...
Source: Arabian Journal of Chemistry - Category: Chemistry Source Type: research