Physics of Gate Modulated Resonant Tunneling (RT)-FETs: Multi-barrier MOSFET for steep slope and high on-current

A new concept of nanoscale MOSFET, the Gate Modulated Resonant Tunneling Transistor (RT-FET), is presented and modeled using 3D Non-Equilibrium Green’s Function simulations enlightening the main physical mechanisms. Owing to the additional tunnel barriers and the related longitudinal confinement present in the device, the density of state is reduced in its off-state, while remaining comparable in its on-state, to that of a MOS transistor without barriers. The RT-FET thus features both a lower RT-limited off-current and a faster increase of the current with VG, i.e. an improved slope characteristic, and hence an improved Ion/Ioff ratio. Such improvement of the slope can happen in subthreshold regime, and therefore lead to subthreshold slope below the kT/q limit. In addition, faster increase of current and improved slope occur above threshold and lead to high thermionic on-current and significant Ion/Ioff ratio improvement, even with threshold voltage below 0.2 V and supply voltage Vdd of a few hundreds of mV as critically needed for future technology nodes. Finally RT-FETs are intrinsically immune to source–drain tunneling and are therefore promising candidate for extending the roadmap below 10 nm.

Research highlights
► Physics of a new nanoscale MOSFET concept is investigated through Quantum simulations.
► The RT-FET is a MOSFET with additional gate controlled tunnel barriers.
► RT-FETs have a lower RT-limited off-current and a high thermionic on-current.
► RT-FETs can achieve improved slope and Ion/Ioff ratios over conventional MOSFETs.
► RT-FETs can have slope below the kT/q limit and are immune to SD tunneling.