Modulation of Schottky Barrier Height of Metal/TaN/n-Ge Junctions by Varying TaN Thickness

This paper demonstrates experimentally the modulation of the Schottky barrier height (SBH) of metal/TaN/n-Ge junctions by varying the TaN thickness in a dual stacked metal layer. The effective SBH for the metal/TaN/n-Ge Schottky junctions, originally pinned at 0.53-0.61 eV, decays to 0.44 eV, the barrier height of TaN/n-Ge, with an increase in the TaN thickness from 0 to 10 nm, independent of the type of metal. Dipole formation at the TaN/Ge interface is proposed to alleviate the metal-induced gap states and shift the pinning level toward the conduction band. The modulation of the SBH can be ascribed to the interdiffusion between the cap metals (Al, Fe, and Ni) and TaN.