Ohmic Contact to n-Type Ge With Compositional W Nitride

By varying composition of the WN_x film electrode, modulation of the Schottky barrier height (SBH) of WN_x/n-Ge contacts was demonstrated. The effective SBH decreased from 0.52 eV for W/n-Ge contact to 0.47, 0.42, and 0.39 eV for WN_x/n-Ge contacts with various nitrogen x components, which were 0.06, 0.09, and 0.15, respectively. Ohmic contact property was achieved when the nitrogen component in WN_x reached x = 0.19. As an explanation, an electrical potential caused by the N-Ge dipoles layer across the WN_x/n-Ge contact interface is proposed to alleviate the Fermi-level pinning effect.