Hamburg 2001 – scientific programme

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DS: Dünne Schichten

DS 31: Postersitzung

DS 31.16: Poster

Tuesday, March 27, 2001, 16:30–17:30, Foyer Saal 4

Effects of the energy on damage production in MeV ion-implanted GaAs — •W. Wesch, E. Wendler, and N. Dharmarasu — Friedrich-Schiller-Universität Jena, Institut für Festkörperphysik, Max-Wien-Platz 1, 07743 Jena

GaAs was implanted with Br ions at energies between 0.6 and 9 MeV and ion fluences between 6x10¹² and 1x10¹⁵ cm⁻², implantations were carried out at room temperature and 100 K. The dose rate was kept constant at 2x10¹⁰ and 8x10¹⁰ cm⁻²s⁻¹, respectively. The damage distributions produced were calculated from RBS/channeling spectra by means of the DICADA program. In the case of room temperature implantation for constant nuclear deposited energy density a decrease of the damage concentration in the maximum of the damage distribution with increasing ion energy is observed. This behaviour is in accordance with the decrease of the nuclear deposited energy per ion and unit length which is due to the increasing range straggling with increasing ion energy. For a given depth this enhanced range straggling is equivalent to a decrease of the local dose rate. According to the model of Morehead and Crowder a decrease of the dose rate is connected with a decrease of the critical temperature for amorphization. Thus, the difference between the implantation temperature and the critical temperature increases which explains the enhancement of in situ annealing with increasing ion energy at room temperature. If the implantations are carried out at 100 K the maximum damage remains almost constant with increasing ion energy. At this temperature which is far below the critical temperature dose rate effects do not occur.