Optimizing AlInGaN/GaN High Electron‐Mobility Transistors for pH Sensing: A Temperature‐Dependent Modeling Approach

A temperature‐dependent current–voltage model is presented to analyze the performance of quaternary AlInGaN/GaN‐based high electron‐mobility transistors (HEMTs) as pH sensors. Using the model, the pH sensing characteristics are evaluated for a temperature range of 100 to 500 K. It is observed that with an increase in the pH values, the drain current falls and the threshold voltage increases. A similar pattern in the drain current and threshold voltage is also observed as a function of the rising temperature. The average value of pH sensitivity is found to be 58.3 mV pH −1 at T = 300K (room temperature) which is close to the Nernstian point 59 mV pH −1 . The calculations at pH levels from acidic pH 2 to basic pH 12, agree well with the available experimental data. The composition Al 0.75 In 0.2 Ga 0.05 N has the maximum sensitivity when compared to the other material compositions at different temperatures across all pH levels for a barrier width of 20 nm.