Sub-Thermionic Steep Switching in Hole-Doped WSe2 Transistors

Decreasing the subthreshold swing (SS) of field-effect transistors (FETs) to sub-60 mV/decade at room temperature can enable next-generation low-power electronics [1]. Here, we demonstrate steep switching $(SS < 5\mathrm{mV}/\mathrm{decade})$ and high on-current $(I_{\mathrm{ON}}\approx 400\mu \mathrm{A}/\mu \mathrm{m})$ in non-uniformly hole-doped WSe2 transistors. By setting up large lateral electric field gradients through spatial variation of doping, we deduce that the abrupt switching behavior is consistent with avalanche (impact ionization [2]) of charge carriers, opening up a new approach to achieve low-power transistors based on ultra-thin 2D materials.