Cold Source Engineering towards Sub-60mV/dec p-Type Field-effect-transistors (pFETs): Materials, Structures, and Doping Optimizations

To break the thermal limit of 60mV/dec sub-threshold swing, this work presents a comprehensive study on the strategy for designing p-type cold source FET (pCS-FET). By using first-principles simulations and quantum-transport modeling method, the source engineering of density of states that governs the CS-FET performance is investigated in terms of CS materials, heterojunction structures, and doping process. It is shown that sub-60mV/decade switching can be realized with various CS materials, including 2D metal materials, Dirac material (graphene) and n-doped semiconductors (Si, MoS
2
). Especially, an excellent SS of ~24 mV/dec over four decades of current can be achieved with n-doped graphene CS. More importantly, a steep slope as low as ~33mV/dec also can be achieved with a simply stacked n-doped Si as the CS.