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 V-G, i.e. an improved slope characteristic, and hence an improved I-on/I-off 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 I-on/I-off ratio improvement, even with threshold voltage below 0.2 V and supply voltage V-dd 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. (C) 2011 Elsevier Ltd. All rights reserved.