Diluted manganese on the bond-centered site in germanium

Abstract

The functional properties of Mn-doped Ge depend to large extent on the lattice location of the Mn impurities. Here, we present a lattice location study of implanted diluted Mn by means of electron emission channeling. Surprisingly, in addition to the expected substitutional lattice position, a large fraction of the Mn impurities occupies the bond-centered site. Corroborated by ab initio calculations, the bond-centered Mn is related to Mn-vacancy complexes. These unexpected results call for a reassessment of the theoretical studies on the electrical and magnetic behavior of Mn-doped Ge, hereby including the possible role of Mn-vacancy complexes.

Lattice position and thermal stability of diluted As in Ge

“…Although previous EC results have indicated that several impurities in Ge not only occupy the substitutional site but also other high-symmetry sites, such as the BC site and the T site, [8][9][10][11][12] an excellent fit to the presented data in Fig. 2 (a-d) which is consistent in all four directions, is obtained by assuming that all As atoms occupy an undisplaced substitutional site.…”

“…It was shown in a direct way that this donor occupies an undisplaced substitutional site in the diamond lattice structure of Ge. Contrary to earlier EC experiments, where several impurities were found to occupy interstitial sites as well as substitutional sites, [8][9][10][11][12] no As atoms were found on any interstitial site or on a displaced substitutional site.…”

“…This technique has repeatedly proven its strength in determining the lattice site of a broad range of ion implanted impurities in Ge [8][9][10][11][12] as well as in several other singlecrystalline materials. [13][14][15][16][17] In particular, recent EC experiments in Ge have shown that this technique is capable of observing small fractions of impurities, both on substitutional and on interstitial sites, such as the bond-centered (BC) site [8][9][10][11][12] or the tetrahedral interstitial (T) site.…”

Direct observation of the lattice sites of implanted manganese in silicon

“…This has been suggested, e.g., for several TMs in Ge. 35,36 Because this ideal configuration is not observed for 3d TMs in Si, it has been proposed that other multivacancy complexes could be involved. In particular, the TM may occupy displaced BC sites inside hexavacancy rings to satisfy the fourfold coordination of neighbor Si host atoms.…”

Electronic properties of manganese impurities in germanium

“…[15] More recently, spectroscopic studies of Ge:Mn have been performed aiming at elucidating the geometry of Mn-related defects in Ge. As suggested by Decoster et al [16] the magnetic behavior of a transition metal impurity strongly depends on its location in the lattice.…”