Session 12B-1

Mechanisms for Low On-State Current of Ge (SiGe) nMOSFETs:
A Comparative Study on Gate Stack, Resistance,
and Orientation-Dependent Effective Masses

 

Abstract

We report the results of a systematic study to understand low drive current of Ge-based nMOSFET. The poor electron transport property is primarily attributed to the intrinsically low density of state and high conductivity effective masses. Results are supported by interface trap density (Dit) and specific contact resistivity (ρc), which are comparable (or symmetric) for both nand p-MOSFETs. Effective masses of electrons, which populate L valleys are large for conductivity and small for the density of states in conventional (100) [110] channel directions, resulting in low electron mobility and carrier concentration in Ge-based nMOSFETs.