COMPOSITE SILICON/METAL NANOSTRUCTURES BY METAL-ASSISTED ETCHING FOR CHEMI-TRANSISTOR SENSORS

This work reports on the use of composite silicon/metal nanostructures (cSiMN) prepared by Metal Assisted Etch-ing (MAE) as highly sensitive material for the fabrication of chemi-transistor gas sensors operating at room tem-perature. As a case-of-study, we investigate the integration of composite silicon/gold nanostructures (cSiAuN) synthesized by MAE in solid-state transistors, namely junction-field-effect transistors (JFET), aimed at the detec-tion of nitrogen dioxide (NO2) down to 100-part-per-billion (ppb). The resulting chemi-transistor sensor, namely cSiAuJFET (Composite Silicon Gold JFET), consists of a p-channel JFET in which the cSiAuN layer is placed on top of the p-channel and acts as a sensing gate. A thorough electrical characterization, both static and dynamic, of the cSiAuJFET sensor is performed in NO2 at concentration of hundreds ppb using synthetic air as carrier gas. Notably, the cSiAuJFET sensors show fast and reliable response to NO2 in the range 100-500 ppb without signifi-cant aging effects, in terms of response times and sensitivity value, up to a few days of continuous operation.