Thickness Engineered Tunnel Field-Effect Transistors Based on Phosphorene

Thickness engineered tunneling field-effect transistors (TE-TFET) as a high-performance ultra-scaled steep transistor is proposed. This device exploits a specific property of 2-D materials: layer thickness-dependent energy bandgaps (E
_g
). Unlike the conventional hetero-junction TFETs, TE-TFET uses spatially varying layer thickness to form a hetero-junction. This offers advantages by avoiding the lattice mismatch problems at the interface. Furthermore, it boosts the ON-current to 1280 μA/μm with 15-nm channel length. Providing higher ON currents, phosphorene TE-TFET outperforms the homojunction phosphorene and the TMD TFETs in terms of extrinsic energy-delay product. TE-TFET also scales well to 9 nm with constant field scaling E = V
_DD
/L
_ch
= 33$ mV/nm. In this letter, the operation principles of TE-TFET and its performance sensitivity to the design parameters are investigated through full-band atomistic quantum transport simulations.