Analytical model of ballistic current for GAA nanowire MOSFET including band structure effects: Application to ring oscillator

Gate-All-Around (GAA) nanowire architecture is aimed to represent the ultimate integration for MOSFET up to dimensions of several nanometers. Very thin nanowires (< 5 nm) are expected to be used in these ultimate devices, for which a new physical phenomenon emerges: the modification of the band structure compared to bulk silicon, which changes the conduction properties and affects the device characteristics. These band structure effects (BSE) are then expected to influence the performances of circuits based on ultra-thin nanowire GAA MOSFETs. In this paper, an analytical model for ballistic current in GAA nanowire MOSFET including the band structure variation is developed to assess the BSE impact on nanowire MOSFET operation. Results at the device level are successfully confronted and validated on numerical tight-binding simulations. The model is further implemented in a circuit simulator and is used to evaluate BSE impact on performances of ring oscillator based on GAA nanowire MOSFET.