Impact of gouy–chapman–stern model on conventional ISFET sensitivity and stability
Ahmed M. Dinar, AS Mohd Zain, F. Salehuddin, M.K. Abdulhameed, Mowafak K. Mohsen, Mothana L. Attiah
Utilizing Gouy–Chapman–Stern model can improve ISFET sensitivity and stability using Stern layer in direct contact with electrolyte in ISFET sensing window. However, this model remains a challenge in mathematical way, unless it’s re-applied using accurate simulation approaches. Here, we developed an approach using a commercial Silvaco TCAD to re-apply Gouy–Chapman–Stern model as ISFET sensing membrane to investigate its impact on sensitivity and stability of conventional ISFET. Sio2 material andhigh-k Ta2O5 material have been examined based on Gouy–Chapman and Gouy–Chapman–Stern models. Results shows that the ISFET sensitivity of SiO2 sensing membrane is improved from ~38 mV/pH to ~51 mV/pH and the VTH shift stability is also improved. Additionally, the results indicate that the sensitivity of Ta2O5 is 59.03 mV/pH that hit the Nearnst Limit 59.3 mV/pH and achieves good agreements with mathematical model and previous experimental results. In conclusion, this investigation introduces a real validation of previous mathematical models using commercial TCAD approach rather than expensive fabrication that paves the way for further analysis and optimization.