Formation of Low-Resistivity Metal/Germanium Contact with Ultra-Thin Interlayer and Plasma Oxidation for n-Channel Germanium FET

Abstract

In this work, the plasma oxidation process is introduced into the metal–interlayer–semiconductor (M–I–S) structure to reduce the contact resistance of the metal/n-type germanium (n-Ge) contact. The GeOx layer formed by the plasma oxidation process acts as a good passivation layer between TiO2 and Ge, and also an additional metal induced gap states (MIGS) blocking layer. From these effects of the GeOx layer, the M–I–S structure with multi-layered interlayer stack, TiO2/GeOx, shows approximately four orders of magnitude of the reverse current density improvement from the M–S contact. This technique can be a solution of the severe Fermi-level pinning (FLP) and the high contact resistance in source/drain (S/D) regions of the n-channel germanium field-effect transistor (FET).