Universal relationship between low-field mobility and high-field carrier velocity in high-κ and SiO₂ gate dielectric MOSFETs

The relationships between velocity, ν, and mobility, μ, are investigated to clarify the effectiveness of μ enhancement to increase ν in short channel FETs with SiO₂ as well as high-κ gate dielectric. The ν-μ relationships were extracted on the basis of accurate understanding of V_sub dependence of μ; V_sub dependences of μ in high-κ, high N_sub, and short-channel FETs were carefully studied and the deviations from the standard V_sub dependence were found in each case. It was found that ν-μ relationship is universal, namely independent of gate dielectrics, in Si nFETs with L _eff of down to 80 nm. Due to lower μ and resultant weaker ν saturation in high-κ FETs, μ booster technologies more significantly contribute to ν and I_on enhancements in short-channel high-κ FETs than in SiO₂ FETs.