Contacts on Si1-x-yGexCy alloys:: Electrical properties and thermal stability

In this work, we have investigated the reactions between Zr and SiGeC alloys using rapid thermal annealing. The interactions of the metal films with the Si1-x-yGexCy alloys have been investigated by using sheet resistance measurements, Rutherford backscattering (RBS), energy dispersive spectroscopy (EDS), and x-ray diffraction. The morphologies of surfaces and interfaces were examined using atomic force microscopy (AFM) and cross-sectional transmission electron microscopy (TEM). The analyses indicated that the C49-Zr(Si1-zGez)(2) phase is the final phase of the reaction. The ternary alloy even annealed at temperature as high as 800 degrees C indicates the same Ge index x, as in the as-deposited Si1-xGex layer. We did not observe any Ge segregation after annealing. The results indicate that Zr may be a good candidate for contacts on IV-IV alloys in terms of thermal stability. In addition, we have studied the electrical properties of Schottky contacts to SiGeC alloys. We have shown that the dependence of the SBH on the metal work function is less pronounced for the alloys than for pure Si. The addition of Ge in the binary alloys always leads to a decrease of the SBH to p type. The incorporation of C results in a large increase of the SBHs and provides the possibility to get field effect on p-type IV-IV alloys by using Schottky contacts. (C) 1998 American Vacuum Society.