2D materials for reducing contact resistivity of metal-semiconductor junction

As the channel resistance of transistor shrinks with continued scale down of complementary metal-oxide-semiconductor technology nodes, lowering external parasitic resistance, especially the contact resistance (Rc), becomes a critical area of focus. The current approach to lower contact resistance is to reduce width of Schottky barrier by using heavily doped semiconductors. However, this method is approaching its limitation because of the solid solubility limit of charged dopants in Si, high leakage current, and dopant profile control.
Here, we insert 2D materials between metal and semiconductor, such as graphene and hexagonal-boron nitride (h-BN) and transition metal dichalcogenides to reduce height of Schottky barrier and contact resistance. In this approach, 2D layers improve the metal/semiconductor contact by modifying the work function of contact metal and thus reducing Schottky barrier height. With the insertion of 2D materials, we achieved Schottky barrier height of less than 0.1 eV and contact resistivity of few nano-ohm cm2. This proposed 2D inserted technique can be used as sub nano-ohm cm2 contacts for metal/n-Si and low Rc contact with new semiconductor materials beyond Si CMOS technology.