Extended Gate Field Effect Transistor-Based N-Type Gallium Nitride as a pH Sensor

The exceptional properties of gallium nitride (GaN) such as distinctive band gap and strong chemical stability make it promising as a semiconductor material to detect and select ions, liquids and gases. Sensing characteristics of an extended gate field effect transistor (EGFET)-based undoped N-type GaN as a pH sensor was investigated by using six buffer solutions with pH range 2-12 at room temperature. Distinctive current-voltage (I-V) characteristics of EGFET with gate controllability were observed in a solution. The surface potential of the membrane at the sensing area is controlled by Ag/AgCl reference electrode via aqueous solution. The sensitivity in terms of reference voltage in the linear region was 24.72 mV/pH with a good linearity. There is another function in the saturation region in the expression via drain-source current (I-DS), and the outputs indicated that to 0.39 (mu A)(1/2)/pH. I-DS sensitivity proved to be a reliable outcome as a linear response along the pH range. As an indicator of the stability and the reversibility of our sensor, we measured the hysteresis with two loops. The results showed a low value of hysteresis depth of 14.98 mV and 13.06 mV for the acidic side, 30.91 and 32.72 for the basic side.

Automated summary

The study investigated the sensing characteristics of undoped N-type GaN-based extended gate field effect transistor (EGFET) as a pH sensor, demonstrating good sensitivity and linearity. Unique current-voltage (I-V) characteristics with gate controllability were observed in the solution. Using six buffer solutions with a pH range of 2-12, the experiment showed a reference voltage sensitivity of 24.72 mV/pH.