Iron in silicon: Interactions with radiation defects, carbon, and oxygen

Abstract

First-principles theory is used to calculate the interactions between interstitial iron or the iron-boron pair and a vacancy, between interstitial iron and a divacancy, oxygen-vacancy pair, self-interstitial, and interstitial carbon, as well as substitutional carbon, interstitial oxygen, and the oxygen dimer in silicon. The structures, charge and spin states, binding energies, and, in some cases, vibrational spectra are predicted. The gap levels are estimated using the marker method. The strongest interactions involve vacancies, result in the formation of pairs of metastable defects, and profoundly change the electrical activity of the component species. Iron also traps at self-interstitial-type defects, but not at interstitial oxygen or substitutional carbon. Several observed but incompletely characterized defects are identified and trends in the behavior of Fe in Si are discussed.

Influence of n+ and p+ doping on the lattice sites of implanted Fe in Si

“…In the case of i-Si 25,26 , we proposed the near-T fraction not to be free interstitial Fe, but probably also bound to vacancy-related defects. This point of view was considerably strengthened in the meantime by the theoretical study 41 published by Estreicher et al in 2008. They predicted that interstitial Fe i assumes metastable positions next to a vacancy or double vacancy, and that around 3 eV are needed for Fe to completely escape from this trap, while the positions of Fe in these Fe i -V and Fe i -V 2 complexes were predicted also somewhat shifted (∼ 0.2-0.3Å) from the ideal T towards the AB sites.…”

“…B − , is a well-known phenomenon [1][2][3]22,23,40 . In the next subsections we discuss each type of observed lattice site that we unambiguously identified, comparing with ab initio calculations 21,40,41 and Mössbauer spectroscopy [42][43][44][45] studies from literature.…”

“…We should now discuss the origin of the near-BC sites. From theoretical calculations it was proposed that a divacancy in Si should trap an Fe atom in a position that is centered between the two vacant Si sites, which corresponds to a BC site 41 …”

Direct observation of the lattice sites of implanted manganese in silicon

“…37 Because this explanation involves metastable complexes, we suggest that more complicated structures, other than single or double vacancies, are involved. For the p + -Si experiment, a different scenario has to be considered, since…”

Lattice location and thermal stability of implanted nickel in silicon studied by on-line emission channeling

“…For clusters constituted by only two vacancies, ideal BC sites might be preferred over other positions. 41,42 On the other hand, for vacancy clusters constituted by more than two vacancies, e.g. 3-6 vacancy clusters, the structural rearrangement after their formation can, for instance, result in a fourfold configuration based on hexavacancy rings where extra Si atoms are incorporated near BC positions to satisfy dangling bonds.…”