Possible observation of ballistic contact resistance in wide Si MOSFETs

In conclusion, using a comparison of our experimental data of R_EXT versus N_S and T to the ballistic FET theory, we have presented experimental evidence on the possible observation of ballistic contact resistance R_B in wide-channel Si MOSFETs. Finally, we note that the ballistic contact resistance R_B represents the ultimate limit of total series resistance R_EXT [8]. This limit for (100) Si is ~ 40 Ω.μm for NFETs and ~ 70 Ω.μm for PFETs at N_S = 1 × 10¹³ cm^-2. Furthermore, this limit of R_EXT is ~ 55 Ω.μm for III-V NFETs at N_S = 1 × 10¹³ cm^-2 with isotropic effective mass m*/m₀ in the 0.02-0.1 range. The value of R_B is slightly higher for III-V NFETs than that for Si NFETs because lower m* and lower valley degeneracy lead to lower number of conducting transverse modes.