Mechanical and Electrical Characterization of Low-resistivity Contact Materials for Mg2Si

In this work, the characterization of different metal-semiconductor contacts on n-type polycrystalline Mg2Si and p-type HMS substrates for the application in thermoelectric devices is presented. Metal (e.g. Au, Cu, Ni, Al, and Ti) contacts were deposited by DC magnetron sputtering or melted onto Mg2Si samples. Moreover, brazing alloy was applied on Mg2Si and HMS samples. Compositional and morphological characterization of the pellets and coatings were obtained by Field Emission Scanning Electron microscopy (FE-SEM) coupled with Energy Dispersive Spectroscopy(EDS). Tribological measurements and in situ FE-SEM observation as a function of temperature were carried out in order to evaluate adhesion properties of the film electrodes deposited onto Mg2Si substrate. The electrical properties of the different metal-semiconductor interfaces were investigated in terms of their Ohmic or Schottky properties. The resistivity of the samples and the interface contact resistance was obtained with I-V characteristics and a custom-built ?-probe apparatus. The lowest contact resistances measured were 4.43×10-5 ? cm2 for a n-type Mg2Si leg and 5.29×10-5 ? cm2 for a p-type HMS, both with a braze Cu electrode.