The use of high temperature Mn⁺ ion implantation onto Ge (100) substrates in view of the fabrication of a group-IV diluted magnetic semiconductor is explored. Different implant conditions have been tested and a large number of different experimental techniques (TEM, EXAFS, EELS, XRD) has been used to investigate the effective dilution of Mn species. Use of relatively low temperatures (240°C) and a Mn⁺ dose of 2·10¹⁶ ions/cm³ reveals to be effective in diluting about 60% of the overall Mn atoms, that occupy substitutional Ge lattice sites. Pure dilution is observed in the subsurface (up to ~35 nm) Ge implanted layer with peak Mn concentration of ~7 at.%. This result has never been achieved in MBE-grown MnGe alloys. In the deeper region of the implanted layer Mn atoms precipitate in amorphous Mn-rich extrinsic clusters (size range 3-15 nm), coexisting with the surrounding diluted Mn_xGe_1-x alloy. Upon annealing at 400°C the clusters evolve in two different ways: smaller ones tend to dissolve, releasing their Mn content to the surrounding host matrix in diluted form; on the contrary, bigger clusters tend to acquire Mn atoms from the surrounding matrix and to crystallize in Mn₅Ge₃ phase. Consistently, MOKE measurements, performed to analyze the magnetic response of the samples, show magnetic signals associated with: i) diluted MnGe semiconductive matrix, ii) amorphous Mn-rich precipitates, iii) Mn₅Ge₃ nanocrystals. In the as-implanted sample, the weak superparamagnetic contribution of amorphous clusters can be easily isolated, while Mn_xGe_1-x diluted semiconductor manifests magnetic hysteresis up to 130 K.

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