An Electrical Analysis of a Metal-Interlayer-Semiconductor Structure on High-Quality Si1-xGex Films for Non-Alloyed Ohmic Contact

Abstract

In this paper, we have investigated the effect of a metal-interlayer-semiconductor (MIS) structure on intrinsic silicon-germanium (SiGe) film which is epitaxially grown by ultra-high vacuum chemical vapor deposition (UHV-CVD). Ultra-thin dielectric materials can alleviate Fermi-level pinning at the metal/Si1-xGex contact region by preventing penetration into the Si1-xGe x of metal-induced gap states (MIGS) from the metal surface. The electrical properties which are the back-to-back current density and specific contact resistivity of the Ti/TiO2/Si1-xGex structure improve at the TiO2 interlayer thickness of 0.5 nm for all kinds of Si1-xGex film with various levels of germanium (Ge) concentration. The case of Si0.7Ge0.3 film, the specific contact resistivity of a Ti/TiO2(0.5 nm)/Si0.7Ge0.3 structure is reduced 80-fold compared to that of a Ti/Si0.7Ge0.3 structure. The effect of the MIS structure has been well demonstrated on Si1-x Ge x film, and as a result this structure is suggested as a novel source/drain (S/D) contact scheme for advanced Si1-xGex complementary metal-oxidesemiconductor (CMOS) technology.