Tunneling Attenuation and Leakage Current in MoS2 Nanoribbon MOSFETs

We study the OFF-state leakage current in quasi-one-dimensional MoS2 nanoribbon (MoS2NR) FETs using ab initio Hamiltonians and quantum transport simulations based on Green’s functions. Complex band structure is computed for these devices and the energy-dependent tunneling attenuation inside the bandgap is obtained. We investigate the tunneling component of the OFF-state leakage for sub-20 nm long and sub-3 nm wide MoS2NR FETs, using the under-the-barrier (UTB) and top-of-the-barrier (ToB) ballistic models. We report that using the parabolically-approximated attenuation overestimates the OFF-state leakage significantly. Furthermore, we demonstrate that all MoS2NR FETs show good tunneling suppression due to high attenuation even for the shortest devices where the OFF-state leakage is under 16.5 nA/μm for nFETs and lower than 22 nA/μm for pFETs.