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Theoretical Calculation and Experimental Verification for Dislocation Reduction in Germanium Epitaxial Layers with Semicylindrical Voids on Silicon
Published on: July 17, 2020
Transition metal impurities on the bond-centered site in germanium
S Decoster1, S Cottenier, B De Vries
1Instituut voor Kern- en Stralingsfysica and INPAC, KULeuven, BE-3001 Leuven, Belgium.
Physical Review Letters
|March 5, 2009
Summary
We found transition metals (TMs) like Fe, Cu, and Ag in germanium occupy both expected substitutional sites and unexpected bond-centered sites, forming impurity-vacancy complexes. An approach to move TMs from active sites to the bond-centered site is also presented.
Area of Science:
- Materials Science
- Solid State Physics
- Computational Materials Science
Background:
- Understanding impurity behavior in semiconductors is crucial for device performance.
- Transition metals (TMs) like Iron (Fe), Copper (Cu), and Silver (Ag) are common impurities in Germanium (Ge).
- The precise lattice location of these impurities influences their electrical and physical properties.
Purpose of the Study:
- To determine the lattice sites of ion-implanted Fe, Cu, and Ag in Germanium.
- To investigate the formation mechanism of impurity-vacancy complexes.
- To develop a method for manipulating the location of TM impurities within the Germanium lattice.
Main Methods:
- Combined experimental approach using emission channeling.
- Ab initio total energy calculations based on density functional theory.
- Analysis of heats of formation to predict stable configurations.
Main Results:
- A fraction of implanted Fe, Cu, and Ag atoms were located at substitutional Ge positions.
- A significant fraction of these impurities were found at an unexpected sixfold coordinated, bond-centered site.
- Calculations indicate the bond-centered site results from vacancies trapping substitutional TM impurities, forming split-vacancy complexes.
Conclusions:
- The study reveals a dual lattice site occupancy for Fe, Cu, and Ag in Germanium.
- Impurity-vacancy complex formation is a key mechanism for the observed bond-centered site occupancy.
- A novel method is demonstrated to controllably shift TM impurities from substitutional to bond-centered sites.
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