Comparative Simulation Study of InGaN and Silicon Channel Stack Oxide Twin Gate Field Effect Transistor Based Ammonia Gas Sensor

This work reports a comparative analysis between Indium Gallium Nitride (InGaN) channel stack oxide twin gate field effect transistor (SO-TG-FET) and Silicon (Si) channel stack oxide twin gate field effect transistor for the detection of ammonia (NH₃) gas. Catalytic metal gate of Cobalt (Co) with stacking of SiO₂/HfO₂ is used to detect presence of NH₃.The interaction of ammonia gas molecules with Co metal gate of SO-TG-FET causes a remarkable variation in the sensitivity parameters like drain current (OFF and ON), surface potential, threshold voltage, switching ratio and transconductance. The OFF current sensitivity (S_IOFF) and threshold voltage sensitivity (S_VTH) of the proposed NH₃ gas sensor has also has been analysed at different value of work function of Cobalt metal gate. The performance of the device has been evaluated under ambient conditions both in presence and absence of ammonia gas at room temperature. Results obtained from the simulation of SO-TG-FET NH₃ gas sensor reveal that the device with InGaN channel material has 117% and 226% greater OFF current sensitivity and switching ratio (at \(\Delta {\phi }_{Metal}\) $\mathrm{\Delta }{\varphi }_{\mathit{Metal}}$ =250 meV) respectively than the device with Silicon channel. The contour plot shows that the concentration of charge carrier is 18% higher in Indium Gallium Nitride channel based ammonia gas sensor as compared to the Silicon channel NH₃ gas sensor, which results in enhanced sensitivity. Additionally, in order to investigate the stability of proposed sensor, the statistical analysis of SO-TG-FET NH₃ sensor is performed by evaluating the coefficient of variation in terms of sensitivity (S_IOFF and S_VTH). The comparative study of SO-TG-FET NH₃ sensor with already developed FET based ammonia sensor demonstrates that proposed sensor is highly selective and sensitive towards NH₃ gas. Furthermore, the impact of temperature variation on device performance has been examined and the result obtained reveals that the device is reliable over wide range of temperature. In order to examine the real time performance and long term stability, transient analysis of the proposed sensor has also been performed.