Schottky barrier height in germanide/Ge contacts and its engineering through germanidation induced dopant segregation

The lack of a stable native germanium oxide has been the main obstacle for the use of Ge in complementary metal oxide-semiconductor CMOS devices. However, recent development of next generation deposited high-k gate dielectrics for Si also allows for the fabrication of high-performance Ge-based metal-oxide-semiconductor field effect transistors (MOSFETs). For the formation of electrical contacts in Ge-based MOSFETs, transition metal germanides, such as Ni- and Pt-germanides, appear to be suitable candidates for this application due to their low resistivity, low formation temperatures (as low as 250degC), and ability to form in self-alignment. In this work, we have characterized the material and electrical properties of nickel and platinum germanide films as Schottky source/drain contacts for Ge-MOSFETs. This paper will focus on the electrical characterization of Ni- and Pt-germanide Schottky contacts on crystalline germanium substrates with particular emphasis on the theoretical analysis of the effect of inversion layer on I-V and C-V characteristics. In addition, the Schottky barrier modulation by germanidation induced dopant segregation will also be discussed.