Experimental study of the amorphous phases of group-IV semiconductors by the^119mSn Mössbauer probe

The amorphous phases of silicon, germanium, and α-tin have been studied by Mössbauer emission spectroscopy on ion-implanted, radioactive^119mSn. Amorphous samples have been produced by ion implantations of various elements and by vacuumevaporation techniques. The same well-defined type of complex spectrum is observed for all investigated amorphous samples. These spectra are characterized by an increase in average isomer shift of (0.15±0.03) mm/s, a line broadening of 20±2%, and the same Debye temperature as compared with spectra of substitutional Sn in the respective crystalline host lattices. The spectra are proposed to originate from Sn atoms incorporated substitutionally in the amorphous host with distorted local surroundings. The recrystallization of the amorphous phase upon thermal and laser annealing has been monitored. After appropriate annealing, spectra characteristic of crystalline materials are observed for most samples. An exception are high-dose, inert-gas implanted samples where different complex defects seem to be formed in the annealing process.