Diffusion and isomer shift of interstitial iron in silicon observed via in-beam Mössbauer spectroscopy

Lattice sites of implanted Fe in Si

“…21,[23][24][25] In 57 Mn→ 57 Fe experiments the intensity of the singlet substitutional center ͑c͒ continuously increases above 100 K and finally remains constant only above 180°C, [23][24][25] while in 57 Fe * studies it only appears above ϳ350°C. 17,20 This difference in temperature may be due to the fact that in 57 Fe * experiments these centers can definitely only be formed during the 140 ns lifetime, while in 57 Mn→ 57 Fe studies they may be formed already by the 57 Mn precursor and survive its decay. In 57 Mn→ 57 Fe experiments above 100°C the "new line" ͑d͒ starts to appear which persists even at 500°C.…”

“…The general picture which has emerged from these studies is that Fe in Si produces four characteristic Mössbauer signals: ͑a͒ a quadrupole-split doublet with ␦ = + 0.20-0.33 mm/ s and E Q = 0.83-1.0 mm/ s ͑at 300 K͒ which results from Fe in a damaged environment 17,[20][21][22][23][24][25] and is sometimes also termed the "amorphous" site; 26 ͑b͒ a singlet of isomer shift ␦ = + 0.76-0.86 mm/ s ͑at 300 K͒ which is without doubt due to interstitial Fe; 17,[20][21][22][23][24][25][26][27] ͑c͒ a second singlet with ␦ = −͑0.08-0.03͒ mm/ s ͑extrapolated to 0 K͒ which originates from substitutional Fe; 17,[20][21][22][23][24][25][26][27] ͑d͒ a second doublet with ␦ = + 0.44-0.51 mm/ s and E Q = 0.6 mm/ s ͑extrapolated to 0 K͒, which has been termed the "unknown" 21 or "new" line 22,24 and is attributed to Fe on interstitial sites paired with a vacancy.…”

Fe diffusion in amorphous Si studied using x-ray standing wave technique

“…Furthermore, diffusivity of isolated Fe impurities in a-Si in a similar temperature range has been found to be several orders of magnitude higher. 10 This wide variation in Fe diffusivity in a-Si points out to different mechanisms of diffusion in the three cases. Fe isolated impurities in Si are known to occupy interstitial positions.…”

The solid state physics programme at ISOLDE: recent developments and perspectives

“…Interstitial Fe is known to exist in two charge states and other methods had been unable to pin down the dependence of the diffusivity of the well-known Fe +/0 charge states for the donor level which is at 0.38 eV above the valance band [17]. MS had measured the diffusivity of interstitial 57 Fe i which had been determined by in-beam experiments by the line broadening caused by diffusional jumps during the lifetime of the Mössbauer state [19]. Gunnlaugsson et al noticed that at temperatures above 500 K there was a clear broadening visible in the lines attributed to Fe i [20], which was attributed to the diffusion of Fe during the Mössbauer lifetime.…”