Different recrystallization patterns of Si+ implanted GaAs

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Abstract
Raman spectroscopy was used in a study of the lattice restoration in Si+ implanted GaAs. Investigated samples differed in the type of primary damage induced by selected implantation parameters. Annealing was carried out by thermal treatment in 40° steps starting at 80 °C. Several well defined stages in recrystallization could be followed; de-amorphization being mostly completed after annealing temperature, Ta, as low as 200 °C, whereas for Ta from 200 to 600 °C various processes of ordering in the crystalline phase were dominant. In this temperature range thermal restoration of the crystal lattice follows quite different patterns depending on the types of primary disorder. Monocrystalline character of the recrystallized layer was not entirely restored, even at Ta=800 °C, but still consisted of nanometer-sized crystallites, ∼25 nm, predominantly oriented to follow the underlying substrate orientation. Various types of defects, breaking translational crystal symmetry, such as linear defects, stacking faults, dislocations, dislocation loops, etc. were still present as seen from the finite size of the monocrystalline regions.