Fermi level dependence of Mössbauer spectroscopic components corresponding to iron interstitials and their clusters in silicon

Mössbauer parameters of Fe-related defects in group-IV semiconductors: First principles calculations

“…42 Extensive measurements in n-and p-type samples, where 57 Fe was introduced by several methods, were also carried out by Yoshida and his group. 13,26,43 Although their data for p-type Si seems to be in line with other reported data (δ = 0.8 mm/s), for n-type material a resonance at δ = 0.40 mm/s has been assigned to Fe 0 i . Since our calculations conflict with this assignment, we investigated several possible sources of error, including (i) increasing the BZ sampling grid to MP-4 3 , (ii) bringing the 3s state of Fe into the valence to be treated within the Kohn-Sham scheme, (iii) including an on-site correction to the exchange-correlation energy by means of the GGA+U +J approach as proposed by Liechtenstein et al 113 (with Hubbard and Hund parameters in the range U = 2-5 eV and J = 0-1 eV), and (iv) using the local density approximation to the electronic exchange-correlation interactions.…”

“…The ISOLDE consortium reported a δ(Fe s ) = −0.04 mm/s peak which is effectively independent of the dopant type and concentration, and was therefore assigned to the neutral charge state of substitutional iron (Fe 0 s ). From the same experiments, neutral and positively charged Fe i defects were assigned to resonances at δ(Fe 0 i ) = 0.72 mm/s and δ(Fe + i ) = 0.78 mm/s in n-type and p- 26,43 Other defects were tentatively assigned using MS, namely a quadrupole-split doublet labeled Fe N with ∆(Fe N ) = 0.51 mm/s and δ(Fe N ) =0.43 mm/s, assigned to an iron-vacancy (Fe i V) pair, 12 and another doublet labeled Fe D which has been associated to Fe in regions damaged by the ion-implantation process, with ∆(Fe D ) = 1.02 mm/s and δ(Fe D ) =0.33 mm/s. 33 Ab-initio calculations of Mössbauer parameters have played an important role in the interpretation and validation of experimental data.…”

Observation of iron impurity diffusion in silicon under bending stress by Mössbauer spectroscopy

“…The rather low statistics of the spectra is mainly due to the extremely low concentration of 57 Fe, which is the only way to provide a solid solution of 57 Fe in Si without forming Fe-silicides. This has been confirmed in a series of earlier experiments from our group on 57 Fe doped Si after annealing at 1,273 K for 1 week [6,7]. It can be clearly seen, however, in Fig.…”

“…Their isomer shifts do not change at all within experimental errors during all measurements. The isomer shifts of the singlet 1, 2 and 3 are −0.12 (3) mm/s, 0.33 (3) mm/s, 0.67 (8) mm/s, respectively, which are in good agreement with those of substitutional Fe s , interstitial Fe 0 i and Fe + i [4][5][6][7]. The third component of Fe + i appears to be too small to discuss precisely in the present experiment, although this component could be more clearly detected before in a simple absorber experiment on the same type of sample.…”

“…We have developed a set-up for 57 Fe Mössbauer spectroscopy combined with an Instron-type tensile testing machine. Mössbauer spectroscopy appears to be an ideal tool to identify lattice sites and charge states of 57 Fe in Si [3][4][5][6], and also to determine the Fe diffusivity through a line broadening if the jump frequency stays within a range between 10 6 and 10 8 jumps/s. In the present paper, we report on an in-situ Mössbauer absorber experiment of a 57 Fe doped n-type Si wafer, on which external bending stress was applied at room temperature.…”