Surface Passivation of Germanium Using SF6 Plasma to Reduce Source/Drain Contact Resistance in Germanium n-FET

Abstract

We demonstrate Fermi-level unpinning and contact resistance reduction by surface passivation using SF6 plasma treatment of a metal/germanium (Ge) contact. A specific contact resistivity (rho(c)) of 1.14 x 10(-3) Omega . cm(2) and 0.31 eV of Schottky barrier height is achieved for a Ti/SF6-treated n-type Ge (n-Ge) (N-d = 1 x 10(17) cm(-3)) contact, exhibiting 1700 times rho(c) reduction from a Ti/nontreated n-Ge contact. A convenient and effective passivation process of the Ge surface is presented to alleviate Fermi-level pinning at metal/Ge contact and lower source/drain contact resistance of Ge n-type field-effect transistors.