Electrostatically doped ballistic transition metal dichalcogenide tunnel field-effect transistors

Designed in a sub-11nm channel double-gate structure is the transition-metal dichalcogenide (TMD) tunnel field-effect transistors (TFETs), electrostatically doped by two top and bottom side gates. The self-consistent solution of the Poisson and Schrödinger equations within the non-equilibrium Green’s function (NEGF) formalism is to carry out the numerical simulations for studying the transfer (I_D–V_GS) and output (I_D–V_DS) characteristics of TFETs. Moreover, device parameters are extracted from I_D–V_GS, charge density, potential profile, and transmission probability. The results are then investigated for various source/drain doping levels, manifesting the versatile TFETs, utilizing only two supply voltages, for diverse functionalities, from low power to high performance. In an analysis of two nominated molybdenum disulfide (MoS₂) and tungsten ditelluride (WTe₂) TFETs, I_ON/I_OFF (on to off-current ratio) = 1.9 × 10¹⁵ and SS (subthreshold swing) = 9 mV/dec is calculated for the prior versus gm (transconductance) and Di (intrinsic delay) of about 4 × 10³ µS/µm and 0.1 ps, respectively, for the latter. Considering a shrunk channel down to 3nm, the device switches remarkably fast with ultra-low power dissipation despite the increased leakage current (diminished I_ON/I_OFF ratio) and subthreshold swing. Additionally, robust functionality is observed for the TFETs operating under 500 K temperature fluctuations.