4.1.1.5 Contributions to ${\it R}_{\mathrm{gs}}$ and ${\it R}_{\mathrm{gd}}$.

The ohmic resistances ${\it R}_{\mathrm{gs}}$ and ${\it R}_{\mathrm{gd}}$ represent a rather macroscopic and concentrated form of the carrier transport near the gate contact. Due to the strongly locally varying carrier concentrations with a depleted barrier layer n$\leq$ $10^{10}$ cm$^{-3}$ and a channel with n$\geq$ $10^{18}$ cm$^{-3}$, and carrier temperatures near the gate of ${\it T}_\mathrm{\nu}$$\geq$ 10$\times$ ${\it T}_\mathrm{L}$ a direct physical interpretation is not suitable as the transport situation is extremely non-linear and thus non-ohmic. However, the information contained in the extraction is to be understood in a behavioral sense. As both a current ${\it I}_{\mathrm{G}}$ and the voltages ${\it V}_{\mathrm{GS}}$ and ${\it V}_{\mathrm{GD}}$ are available, the effective impedances ${\it R}_{\mathrm{gs}}$ and ${\it R}_{\mathrm{gd}}$ can be calculated. Especially ${\it R}_{\mathrm{gs}}$ does supply a high amount information, e.g. for compact noise modeling [230].