Analytical Prediction of Highly Sensitive CNT-FET-Based Sensor Performance for Detection of Gas Molecules

In this study, a set of new analytical models to predict and investigate the impacts of gas adsorption on the electronic band structure and electrical transport properties of the single-wall carbon nanotube field-effect transistor (SWCNT-FET) based gas sensor are proposed. The sensing mechanism is based on introducing new hopping energy and on-site energy parameters for gas-carbon interactions representing the charge transfer between gas molecules (CO2, NH3, and H2O) and the hopping energies between carbon atoms of the CNT and gas molecule. The modeling starts from the atomic level to the device level using the tight-binding technique to formulate molecular adsorption effects on the energy band structure, density of states, carrier velocity, and I-V characteristics. Therefore, the variation of the energy bandgap, density of states and current-voltage properties of the CNT sensor in the presence of the gas molecules is discovered and discussed. The simulated results show that the proposed analytical models can be used with an electrical CNT gas sensor to predict the behavior of sensing mechanisms in gas sensors.