An Extended-Gate Field-Effect Transistor With Low-Temperature Hydrothermally Synthesized SnO2 Nanorods as pH Sensor

Abstract

An extended-gate field-effect transistor (EGFET) with low-temperature hydrothermally synthesized SnO2 nanorods as the pH sensor was demonstrated for the first time. The SnO2 nanorod sensor exhibited the higher sensitivity of 55.18 mV/pH and larger linearity of 0.9952 in the wide sensing range of pH 1-13 with respect to the thin-film one. The nearly 15% sensitivity enhancement for such a sensor was attributed to the high surface-to-volume ratio of the nanorod structure, reflecting larger effective sensing areas. The characteristics of the output voltage versus sensing time also indicated good reliability and durability for the SnO2 nanorod sensor. Furthermore, the hysteresis was only 3.69 mV after the solution was changed as pH7 --> pH3 --> pH7 --> pH11 --> pH7.