Fin-Width Scaling of Highly Doped InGaAs Fins

We study the impact of fin-width scaling on transport in highly doped InGaAs fins and the effect of digital etch (DE). Our experiments suggest the existence of a 10-nm-wide “deadzone” on each side of the fin that does not contribute to the transport. The extent of the deadzone cannot be mitigated by DE nor sidewall passivation. Simulations suggest that the Fermi-level pinning and its associated subsurface depletion region alone cannot explain the relatively wide deadzone that is measured. We propose an explanation based on the combination of Fermi-level pinning and mobility degradation as the fin width scales down. This leads to an apparent wider deadzone than accounted by the Fermi-level pinning alone.