Low-energy implantation of Si and Sn into GaAs

(100) GaAs was implanted with 29Si+ at energies of 10 keV or 20 keV and 119Sn+ at an energy of 60 keV. The doses used for the Si+ implants were from 1 x 1013 cm-2 to 1 x 1016 cm-2, whereas the Sn+ doses ranged from 1.5 x 1012 cm-2 to 1.5 x 1015 cm-2. Implanted samples were rapidly thermal annealed (RTA) in either an argon or arsine ambient at 950 degrees C or 900 degrees C for 12 seconds. Transmission electron microscopy (TEM) results indicate that the annealing ambient has a dramatic effect on the defect annealing kinetics for 10 keV implants but not the 20 keV Si+ implants. For the 10 keV implants reducing arsenic loss via use of an arsine ambient or a Si3N4 cap results in a dramatic decrease in the dislocation loop density. The defect morphology is not related to the as implanted morphology (amorphous or crystalline) but is related to the species. Hall effect measurements reveal an increase in the mobility by a factor of 1.5 times for high dose Si+ and Sn+ implanted samples when RTA was carried out in an arsine instead of an argon ambient