Evaluation of the Coulomb-limited mobility in high-κ dielectric metal oxide semiconductor field effect transistors

An efficient numerical method for the evaluation of the Green’s function used in the calculation of the Coulomb-limited electron mobility in high-κ metal oxide semiconductor field effect transistors is presented. This simple method is applicable to gate stacks with an arbitrary number of layers of varying dielectric permittivity. A charge profile with varying dielectric profile is demonstrated to show an increase in Coulomb-limited mobility of 16% in comparison to a point charge located at the interface. A metal gate reduces the scattering potential due to its infinite dielectric constant which leads to lesser impact of charge in comparison to a polysilicon gate. The Coulomb-limited mobility for devices having identical equivalent oxide thickness of 0.5–0.8 nm with (a) a hafnium silicate interfacial layer (IL) and (b) zero IL is presented.