A Simple Approach to Quantum Confinement in Tunneling Field-Effect Transistors

We present an approach to account for quantum confinement in tunneling field-effect transistors (TFETs) based on the use of a nonlocal band-to-band tunneling model for carrier injection along with a self-consistent Schrödinger-Poisson model. Confinement will be considered to take place in one dimension, with the corresponding subband quantization of the conduction and valence bands derived from it. As a result of this quantization, the formerly continuous conduction and valence bands become forbidden states, and tunneling is assumed to occur between their first bound states. This causes an increase of the effective bandgap and, subsequently, of the tunneling barrier width, which greatly affects the total current in the device. Results corresponding to double-gate TFETs with different thicknesses show clear differences in their transfer characteristics when comparing the quantum approach including confinement to the semiclassical one.