A novel high mobility In1-xGaxAs cylindrical-gate-nanowire FET for gas sensing application with enhanced sensitivity

In this paper, Cylindrical Gate Nanowire FET (CGNWFET) is designed with highly doped III-V group compound Indium-gallium-arsenide (In1-xGaxAs) as the channel material. Based on the proposed structure, the hydrogen (H2) and oxygen (O2) gas sensors are designed for enhanced sensitivity. Palladium (Pd) is used as a gate electrode in H2 gas detection whereas silver (Ag) in O2 gas detection because of their sensitivity towards that gas. As the metal work function at gate changes with the presence of gas on it, there is a change in Ioff, Ion and threshold voltage (Vth) which can be taken as sensitivity parameters for sensing the gas molecules. The dimensional parameters varied to check the sensitivities are radius and length of the device. When the sensitivity of proposed In1-xGaxAs CGNWFET is compared with conventional Silicon (Si) CGNWFET, In1-xGaxAs CGNWFET shows enhanced sensitivity. Result shows that as work function varies as 50, 100, 150 and 200 meV for Pd/Ag-metal at gate, the sensitivity enhancement with In1-xGaxAs CGNWFET based H2/O2 gas sensors are 3.27%, 9.11%, 17.02%, 30.18% and 2.59%, 5.78%, 7.11%, 12.17% respectively. Different dielectric materials at the gate are also analyzed. Higher sensitivity is observed for higher dielectric value. Thus, In1-xGaxAs proves to be a strong candidate for designing CGNWFET based sensors for enhanced sensitivity.