The Mechanism of Schottky Barrier Modulation of Tantalum Nitride/Ge Contacts

Abstract

In this letter, we discuss the mechanism of Schottky barrier height (SBH) modulation of the TaN/Ge contact by varying the nitrogen concentration in the TaN. The Fermi level, which is strongly pinned near the valence band edge of Ge, moves to the conduction band edge of Ge with higher nitrogen concentration in the reactive sputtered TaN. This SBH modulation is attributed to the presence of an electric dipole induced by Ge-N bonds at the interface of the TaN/Ge contact. This SBH modulation due to the semiconductor-nitrogen bonds at the interface is not specific to TaN/Ge, but rather is a general feature in various transition-metal nitride systems on various semiconductors.