Point-Defect Generation in Ni-, Pd-, and Pt-Germanided Schottky Barriers on N-Type Germanium Substrates

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 (DLTS). The germanidation is achieved by a Rapid Thermal Annealing (RTA) step between 300 and 500oC of a 30 nm sputtered metal layer. Contrasting behaviour is found between Ni, on the one hand, and Pd and Pt, on the other: in-diffusion of nickel is found starting from 400oC, while in the second case, vacancy-related deep levels have been observed at the lower RTA temperatures. Evidence will be 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 (I-V) characteristics of the obtained metal-germanide Schottky barriers will be discussed.