Sputtered PT/PD Bimetallic Electrode on P-Type Silicon for Room Temperature Ammonia Sensing

This study introduces a room temperature ammonia sensor fabricated by sputtering Pt/Pd bimetallic electrodes on p-type silicon substrate. The sensing mechanism is based on the oxygen adsorption-desorption process, in which adsorbed oxygen forms a hole accumulation layer reducing the surface resistance, and ammonia reacts with adsorbed oxygen ions to release electrons, thereby increasing the surface resistance. The I-V characteristic curves reveal an ohmic contact between Pt/Pd electrode and p-type silicon. The sensor demonstrates 12.02% response to an ammonia concentration of 1%, with a response time of 94.2 s and a recovery time of 295.3 s. Meanwhile, the sensor can achieve very low limit of detection (LoD) down to 100 ppm. The sensor with high sensitivity makes it valuable for ammonia detection in industrial and agricultural applications.