On Backscattering and Mobility in Nanoscale Silicon MOSFETs

The DC current-voltage characteristics of an n-channel silicon MOSFET with an effective gate length of about 60 nm are analyzed and interpreted in terms of scattering theory. The experimental results are found to be consistent with the predictions of scattering theory - the drain current is closer to the ballistic limit under high drain bias than under low drain bias, and the on-current in strong inversion is limited by a small portion of the channel near the source. The question of how the low- and high-
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drain currents are related to the near-equilibrium, long-channel mobility is also addressed. In the process of this analysis, theoretical and experimental uncertainties that make it difficult to extract numerically precise values of the scattering parameters are identified.