Study of High-Performance Ge pMOSFET Scaling Accounting for Direct Source-to-Drain Tunneling

Drift-diffusion models are used in conjunction with Monte Carlo simulations to study and compare the scalability of germanium (Ge) versus silicon (Si) p-channel double-gate MOSFETs near the end of the technology roadmap. Direct source-to-drain tunneling (DSDT) and uniaxial compressive stress effects are taken into account. The higher dielectric constant of Ge results in degraded short-channel effects and lower drive currents for a given off-state leakage specification. With large compressive uniaxial channel stress (1.5 GPa), Ge can outperform Si for gate lengths (L_g) greater than 15 nm. Due to its lower effective hole transport mass, Ge suffers more from DSDT, resulting in degraded p-channel MOSFET performance at very short L_g.