Study on Light and Temperature Properties of AlN pH-Ion-Sensitive Field-Effect Transistor Devices

Aluminum nitride (AlN) thin films were deposited by rf sputtering in an investigation on surface potential properties and hydrogen ion sensing characteristics. The pH sensitivity and surface potential of the produced AlN thin films were analyzed. AlN pH-ion-sensitive field-effect transistor (ISFET) devices have a high pH sensitivity (∼53 mV/pH) at pHs of 1–11. However, light exposure and temperature effects are very critical for ISFET applications. In this study, the light effect and temperature characteristics for the pH response based on AlN/SiO 2 sensing gate ISFET are emphasized. The influence of light and temperature on AlN pH-ISFET behavior under various light intensities (0–4000 lx) and ambient temperatures (5–65°C) is examined. The results show that incident light results in an increased leakage current and a decreased pH sensitivity interference. The pH response of the AlN pH-ISFET was in the 48–57 mV/pH range that was also influenced by the ambient temperature.