Point-Defect Generation in Ni-, Pd-, and Pt-Germanide Schottky Barriers on n-Type Germanium

Abstract

In this paper, the creation of point defects in n-type germanium by Ni-, Pd-, or Pt-germanidation is investigated by means of deep-level transient spectroscopy. The Pt- and Pd-germanidation is achieved by a ramped annealing step up to 300 and 500°C of a 30 nm Ar-ion sputtered metal layer. Contrasting behavior is found between Ni, and Pd and Pt; indiffusion of nickel is found starting from 400°C, while in the second case, vacancy-related deep levels have been observed at lower rapid thermal annealing temperatures. Evidence is provided that these defects are most likely formed during the sputtering of the heavy metal atoms, introducing radiation damage in the Ge substrate. Finally, the impact of these deep levels on the current-voltage characteristics of the obtained metal-germanide Schottky barriers is discussed.