Study on the hysteresis effect of pH-ISFET based on Beckman Φ™ 110 (Si3N4 gate pH-ISFET)

In this study, the commercial manufacture Beekman Phi(TM) 110 (Si3N4 gate pH-ISFET) was acted as the sensitive membrane of pH-ISFET. The experimental results show that the Si3N4 material has a fairly high response, and the pH sensitivity was obtained 56.94 mV/pH in a concentration range between pH 1 and pH 11 at room temperature. In our experiment, we use Keithley 236 Semiconductor Parameter Analyzer to measure the drain current (I-DS) versus gate voltage (V-G) curve of Si3N4 ISFET Over a pH range from 1 to 11 at room temperature. The constant voltage-current circuit and time-voltage recorder were used to measure the hysteresis curve of Beekman Phi(TM) 110 (Si3N4 gate pH-ISFET). The same procedure was also applied to a-Si:H gate pH-ISFET, which fabricated in our laboratory From the I-Ds versus V-G and hysteresis curve, we can obtain that the pH sensitivity was 56.94 mV/pH at constant temperature (25 degrees C) and hysteresis widths of Beekman Phi(TM) 110 (Si3N4 gate pH-ISFET) and a-Si:H gate pH-ISFET in the larger pH site are larger than in the smaller pH site, and the hysteresis width increased with the increasing loop time and measuring path.