Ohmic contact formation on n-type Ge by direct deposition of TiN

We succeeded in Ohmic contact formation on an n-Ge substrate by direct sputter deposition from a TiN target and subsequent postmetallization annealing (PMA) at 350°C. The Schottky barrier heights of the TiN/n-Ge and TiN/p-Ge contacts were 0.18 eV and 0.50 eV, respectively, and were maintained up to a PMA temperature of 550 °C. These electrical characteristics are likely to be associated with an approximately 1-nm-thick interlayer formed at a TiN/Ge interface, which leads to the alleviation of the Fermi level pinning. We demonstrated the validity of the TiN/n-Ge contact using an n+ /p junction, which showed an excellent ideal factor of n=1.01.