Ohmic contact on n-type Ge using Yb-germanide

Abstract

Poor ohmic contact by Fermi-level pinning to valence band (EV) edge is one of the major challenges for germanium (Ge) n-type metal-oxide-semiconductor field-effect transistor (nMOSFET). Using low work-function rare-earth ytterbium (Yb), good ohmic contact on n-type Ge with alleviated Fermi-level pinning was demonstrated. Such ohmic behavior depends strongly on the germanide formation condition, where much degraded ohmic contact at 600 degrees C rapid thermal annealing is due to the lower Yb/Ge composition found by energy-dispersive x-ray spectroscopy. The ohmic behavior of Yb-germanide/n-type-Ge has high potential for future high-performance Ge nMOSFET application. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4768700]