Sensing Performance of Stable TiN Extended-Gate Field-Effect Transistor pH Sensors in a Wide Short Annealing Temperature Range

In this letter, the structural properties and sensing performances of TiN sensing films deposited on a n+-type Si through the reactive DC sputtering method with rapid thermal annealing at a wide temperature range of 200 °C to 800 °C were investigated for extended-gate field-effect transistor (EGFET) pH sensors. We used X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy to study the structural characteristics of these films. These TiN EGFET sensors exhibited almost the same sensing performances, such as pH sensitivity ~58 mV/pH), hysteresis voltage ~2 mV), and drift rate (~0.45 mV/h), indicating that they contained similar or identical in the film composition and surface roughness.