Atomic scale characterization of ion-induced amorphization of GaAs and InAs using perturbed angular correlation spectroscopy

The perturbed angular correlation technique has been utilized to understand the production and nature of the implantation induced crystalline to amorphous transformation in GaAs and InAs. This technique, which is based upon the nuclear hyperfine interaction of the electric-quadrupole moment of the probe nucleus with the electric field gradient from extra nuclear charges, requires introduction of radioactive probe nuclei in host material. The radioactive probes 111In/111Cd were produced with the 14UD heavy-ion accelerator via nuclear reaction that recoil implants the 111In nuclei deep into single crystals of GaAs (1 0 0) and InAs (1 0 0). After removal of radiation damage, caused by recoil implantation, single crystals of GaAs (1 0 0) and InAs (1 0 0) were implanted with stable 74Ge ions (MeV) over a wide dose range at liquid nitrogen temperature. The irradiated samples were investigated with respect to the damage production. The crystalline, disordered and amorphous probe environments were identified from the measurement. The evolution of damage is described within the framework of different amorphization models. In GaAs, amorphization is obtained by direct-impact amorphization and by the growth of amorphous zones due to defect-stimulation at crystalline/amorphous interface. In InAs, the amorphization is first initiated by accumulation of simple point defects and then direct-impact/defect-stimulated mechanism contributes to further stimulate the transformation.