Ion mixing of semiconductor layered-structures

Abstract

This research is a collaborative program between the University of California at San Diego and Cornell University to investigate the phenomenon of ion mixing in semiconductor layered structures. The research effort also involves interactions with Oak Ridge National Laboratory under the Surface Modification and Characterization Collaborative Research Center Program. During the current period of investigation, we investigated parameters that could affect ion-mixing rates in semiconductors. We found that the use of shallow dopants as the mixing ion did not increase the mixing rate, thus indicating that electrically active ions (or the Fermi level) do not play a significant role in ion-mixing. On the other hand, the presence of mismatch strain in Ge/Si layered structures can affect the mixing rate, especially in the temperature independent regime. Mismatch strain can also affect the solid-phase regrowth kinetics of amorphous layers of Ge-Si alloys. In summary, we found that ion mixing kinetics depend primarily on the ion and the target mass and the target temperature. Mixing rates can also be affected, to a certain extent, by thermodynamic driving forces (such as the cohesive energy and the stored strain energy of the system). Impurities do no play a significant role in mixing kinetics. 1 fig.,more » 1 tab.« less