Infrared Transmission of Ge:Mn Thick Films Prepared by Ion Implantation and Post-Annealing

Aproximately 3 micrometer thick Ge:Mn films were prepared by low temperature ion-implantation followed by post-annealing. XRD, SIMS, magnetometry and infrared transmission (100-6500 cm^-1) were used to characterize the films. The average Mn concentration in the amorphous implanted films is less than 0.3%. Annealing causes approximately 40-70% of Mn atoms to migrate to Mn-rich clusters or form Mn₅Ge₃ while the remainder enters the Ge lattice and creates free holes. If annealed at high enough temperature the amorphous films become polycrystalline. Solid phase epitaxy does not occur. A Drude peak and structure in the mid-infrared absorption observed by infrared transmission provide evidence for free holes. The data suggest that the maximum solubility of Mn in Ge is less than 0.08 %.