Electrical modelling and design insight of a vertically movable gate field effect transistor for physical sensor applications

A novel electrical modelling for a vertically movable gate field effect transistor (VMGFET) for sensing applications is conducted. Presented is the manipulation of threshold voltage and drain current of the VMGFET as a function of the effective charge density and the air gap between the gate and the substrate body. The usage of the VMGFET in depletion mode, while operating in the saturation region, is proposed to prevent an electrostatic attraction between the suspended gate and substrate and to have a linear response of drain current over a varying air gap. The sensitivity of the VMGFET is simulated and shows a constant slope by changing the air gap under the operating conditions, such as working in depletion mode and operating in the saturation region. The sensitivity independence of the gate position is desirable when the VMGFET is applied for physical sensor applications.