An infrared transmission study of Ge:Mn thick films prepared by ion implantation and post-annealing

Ge.Mn thick films (t approximate to 3 mu m) with low average Mn concentration (<0.3%) were prepared by ion implantation at 77 K followed by either conventional or flashlamp annealing. The films were characterized by x-ray diffraction, secondary ion mass spectrometry, magnetometry, and infrared transmission (100-6500 cm(-1)). Post-annealing at a 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 Mn5Ge3, while the remainder enters the Ge lattice substitutionally creating free holes. Evidence for free holes comes from the 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%. Published under license by AIP Publishing.