Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Ge:Mn thick films (t$\approx 3\mu$m) with low average Mn concentration (< 0.3 %) were prepared by ion implantation at 77K followed by either conventional or flash lamp annealing. The films were characterized by Xray diffraction, Secondary Ion Mass Spectrometry, magnetometry and infrared transmission (100-6500 cm^{-1}). Post-annealing at high enough temperature recrystallizes the amorphous Ge:Mn films without significant migration of Mn to the surface while solid phase epitaxy does not occur, resulting in polycrystalline films. Annealing causes an estimated 50-80\% of the implanted Mn to migrate to Mn-rich clusters or form Mn_5Ge_3 while the remainder enters the Ge lattice substitutionally creating free holes. Evidence for free holes comes from structure in the mid-infrared absorption coefficient that is similar to previous observations in p-type Ge. The data suggest that the maximum solubility of Mn in the Ge crystalline lattice has an upper limit of <0.08%.