Fermi-level depinning in germanium Schottky junction using nitrogen plasma treatment

Fermi-level depinning in germanium (Ge) through nitrogen (N2) plasma treatment is demonstrated. The Ge surface was exposed to N2 plasma for 1 min without heat treatment, resulting in the formation of 2.5 nm-thick GeOxNy layer with uniform surface and interface morphologies. Ohmic and Schottky behaviours were obtained for Al contacts to N2 plasma-treated n- and p-type Ge with barrier heights of 0.09 and 0.40 eV, respectively. Fermi-level depinning could be attributed to the reduction in interface states caused by the passivation of Ge surface by highly uniform GeOxNy layer.