Fe-implanted 6H-SiC: Direct evidence of Fe3Si nanoparticles observed by atom probe tomography and 57Fe Mössbauer spectroscopy

Abstract

In order to understand ferromagnetic ordering in SiC-based diluted magnetic semiconductors, Fe-implanted 6H-SiC subsequently annealed was studied by Atom Probe Tomography, 57Fe Mössbauer spectroscopy and SQUID magnetometry. Thanks to its 3D imaging capabilities at the atomic scale, Atom Probe Tomography appears as the most suitable technique to investigate the Fe distribution in the 6H-SiC host semiconductor and to evidence secondary phases. This study definitely evidences the formation of Fe3Si nano-sized clusters after annealing. These clusters are unambiguously responsible for the main part of the magnetic properties observed in the annealed samples.

Fe implantation effect in the 6H-SiC semiconductor investigated by Mössbauer spectrometry

“…Theodoropoulou et al showed that 5% of Fe atoms implanted in the 6H-SiC polytype lead to a ferromagnetic material at a temperature of about 250 K. 11 No secondary phase was detected in their samples. Similar findings have been reported by Pearton et al 12 and Stromberg et al 13 Indeed, these authors carried [14][15][16] The formation of nano-sized particles of nano-metric size is partly responsible for the magnetic properties observed on their samples after annealing.…”

“…Moreover, this Fe 3 Si phase is contained in the biggest nanoparticles included in this sample, as showed in Ref. 15. The magnetic components due to this phase represent (28.3 þ 17.1 ¼ 45.4) of the whole area of this spectrum when the Fs (ferro) component only represents 14%.…”

“…It corresponds to the Fe atoms diluted in the matrix because for this annealing, the sample contains an amount of nano-particles (not or slightly ferromagnetic) that is too small, which cannot explain the magnetism of this sample. 15 The Fs (para) and Fei (C) fractions represent approximately 43% and 47% of the whole area of the spectrum. The Fs (para) fraction is slightly reduced for the 900 C annealed sample compared to the as-implanted sample.…”

“…The two other components are attributed to magnetic phases and mainly to the Fe 3 Si phase which are contained in nanoclusters, as already observed. 15 Table II shows the parameters used to fit the M€ ossbauer spectra of the 550 C implanted samples. After annealing at 900 C [ Fig.…”

Probing the Origins of Magnetism in 2 at.% Fe-implanted 4H-SiC

“…This phenomenon has been experimentally confirmed; ferromagnetic ordering appears at Curie Temperatures of 50, 250 and 270 K in Ni, Mn and Fe-implanted 6H-SiC [9]. High Curie Temperatures were also achieved in other TM-doped SiC semiconductors [10][11][12][13][14].…”