Germanium MOS: An Evaluation from Carrier Quantization and Tunneling Current

Ge is promising as an alternative channel material due to its high carrier mobility. In this work, we report an evaluation of Ge MOS from quantization and gate tunneling current simulations. Key findings are: (1) Electron quantization effect is stronger and thus more important in Ge than in Si, and results in smaller inversion capacitance in NMOS. (2) Using constant inversion charge for supply voltage V_DD scaling, moderate reduction in inversion charge is required to meet ITRS roadmap, which can be achieved with high mobility channel. (3) Due to its smaller electron mass and resulting higher electron quantization energy, Ge MOS shows considerably larger gate tunneling current than Si MOS for the same gate dielectric. (4) High-K gate dielectrics are required for low leakage; however, significant challenges exist in the formation of high quality interface layer between high-K and Ge.