In this paper design and simulation of an improved depletion-mode n-channel nanoelectromechanical field effect transistor (NEMFET) at 300K is reported. The designed NEMFET is based on NEMS technology and fully compatible with CMOS fabrication process. A NEMFET is composed of a NEM relay and a MOSFET and comprises a movable gate and a semiconductor part, so that the flowing current is always in the semiconductor part. The nanomechanical movable gate was a bossed doubly clamped beam and simulated by COMSOL Multiphysics software and the electrical part was designed and simulated by ATLAS software. The designed NEMFET had a 25 nm length, 100 nm width and 5.2 nm thicknesses. Optimization was done by applying two 8.5 nm spaces, one between source to gate and the other between gate to drain. Simulation results show in the proposed structure, sub-threshold swing was decreased to 86 mV/dec and the Ion/Ioff ratio was increased to 8.68×104. Manuscript profile