Simulation of Gate-All-Around Tunnel Field-Effect Transistor with an n-Doped Layer

We propose a gate-all-around tunnel field effect transistor (GAA TFET) having a n-doped layer at the source junction and investigate its electrical characteristics with device simulation. By introducing the n-doped layer, band-to-band tunneling area is increased and tunneling barrier width is decreased. Also, electric field induced by gate bias is increased by the surrounding gate structure, which makes it possible to obtain a more abrupt band-bending. These effects bring about a significant improvement in on-current and subthreshold characteristics. GAA TFET with n-doped layer shows subthreshold swing at Id =1nA/µm of 32.5mV/dec, average subthreshold swing of 20.6mV/dec. With comparison to other TFET structures, the merits of the proposed device are demonstrated and performance dependences on device parameters are characterized by extensive simulations.