Lattice damage and
evolution in 6H-SiC under He+ ion irradiation have been
investigated by the combination of Rutherford backscattering in channeling
geometry (RBS/C), Raman spectroscopy, UV–visible spectroscopy and transmission
electron microscopy (TEM). 6H-SiC wafers were irradiated with He ions at a fluence
of 3 × 1016 He+cm−2 at
600 K. Post-irradiation, the samples were annealed in vacuum at different
temperatures from 873 K to 1473 K for isochronal annealing
(30 min). Thermally annealed He irradiated 6H-SiC exhibited an increase in
damage or reverse annealing behavior in the damage peak region. The reverse
annealing effect was found due to the nucleation and growth of He bubbles. This
finding was consistent with the TEM observation. The thermal annealing brought
some recovery of lattice defects and therefore the intensities of Raman peaks
increased and the absorption coefficient decreased with increasing annealing
temperature. The intensity of Raman peak at 789 cm−1 as a
function of annealing temperature was fitted in terms of a thermally activated
process which yielded activation energy of 0.172 ± 0.003 eV.
Highlights
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The reverse annealing effect was founding in the damage peak region.
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The intensities of Raman peaks increased with annealing temperature.
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The absorption coefficient decreased with annealing temperature.
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After annealing at 1273 K, over-pressurized bubbles formed in the damage
peak region.
Source:
Vacuum
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