A deep-level transient spectroscopy study of transition metals in n-type germanium

The deep-level parameters of a number of technological relevant transition metals-Hf, Ti, Cr, Fe, Co and Ni-in n-type germanium have been studied by deep-level transient spectroscopy (DLTS). The metals have been introduced by ion implantation followed by annealing at 500 degrees C for 5 min. In most cases the annealing treatment is sufficient to remove the implantation point defects from the substrate, leaving only metal-related electron traps in the spectra. From the fact that for each metal, one (or more) peaks at a different position and with a different activation energy is observed, it is concluded that levels specific for the individual metals have been detected. This is further validated by the observation that the corresponding trap concentration increases with the implantation dose. In some cases, e.g. Hf, we believe that it is the first observation of the impurity-related deep electron traps in germanium. (C) 2006 Published by Elsevier Ltd.