Maximum metallic conductivity in Si-MOS structures

We found that the conductivity of the two-dimensional electron system in Si metal-oxide-semiconductor structures is limited to a maximum value, $G_{\max },$ as either density increases or temperature decreases. This value $G_{\max }$ is weakly disorder dependent and ranges from 100 to ${140e}^2/h$ for samples whose mobilities differ by a factor of 4.