Nitrogen Implantation and Diffusion in Crystalline Germanium: Implantation Energy, Temperature and Ge Surface Protection Dependence

Abstract

In the present work nitrogen (N2+) has been implanted in crystalline germanium at a constant dose and its diffusion has been studied as a function of implantation energy, annealing temperature and various capping layers deposited on substrate surface. Nitrogen diffusion in germanium appears to be, as in the case of silicon, anomalous toward the capping layer/germanium interface not obeying the second Fick's law. In addition, it appears independent on the capping layer composition. As the implantation energy increases, characteristic nitrogen pileups appear in the region beyond the former amorphous/crystalline interface, attributed to the formation of nitrogen-Ge point defects (in particular interstitials) clusters. There is an evidence that N diffusion in Ge is related to the presence of Ge interstitials gradients maintained during post-implantation annealing between the capping layer/Ge interface and the region beyond the former amorphous/crystalline interface of the substrate. This unique diffusion behavior of N could find applications in Ge based MOS (Metal-Oxide-Semiconductor) technology as proposed in the body of the present article.