Ion beam induced defects in solids studied by optical techniques

J. D. Comins, G. O. Amolo, T. E. Derry, S. H. Connell, R. M. Erasmus, M. J. Witcomb

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Optical methods can provide important insights into the mechanisms and consequences of ion beam interactions with solids. This is illustrated by four distinctly different systems. X- and Y-cut LiNbO3 crystals implanted with 8 MeV Au3+ ions with a fluence of 1 × 1017 ions/cm2 result in gold nanoparticle formation during high temperature annealing. Optical extinction curves simulated by the Mie theory provide the average nanoparticle sizes. TEM studies are in reasonable agreement and confirm a near-spherical nanoparticle shape but with surface facets. Large temperature differences in the nanoparticle creation in the X- and Y-cut crystals are explained by recrystallisation of the initially amorphised regions so as to recreate the prior crystal structure and to result in anisotropic diffusion of the implanted gold. Defect formation in alkali halides using ion beam irradiation has provided new information. Radiation-hard CsI crystals bombarded with 1 MeV protons at 300 K successfully produce F-type centres and V-centres having the I3- structure as identified by optical absorption and Raman studies. The results are discussed in relation to the formation of interstitial iodine aggregates of various types in alkali iodides. Depth profiling of I3- and I5- aggregates created in RbI bombarded with 13.6 MeV/A argon ions at 300 K is discussed. The recrystallisation of an amorphous silicon layer created in crystalline silicon bombarded with 100 keV carbon ions with a fluence of 5 × 1017 ions/cm2 during subsequent high temperature annealing is studied by Raman and Brillouin light scattering. Irradiation of tin-doped indium oxide (ITO) films with 1 MeV protons with fluences from 1 × 1015 to 250 × 1015 ions/cm-2 induces visible darkening over a broad spectral region that shows three stages of development. This is attributed to the formation of defect clusters by a model of defect growth and also high fluence optical absorption studies. X-ray diffraction studies show evidence of a strained lattice after the proton bombardment and recovery after long period storage. The effects are attributed to the annealing of the defects produced.

Original languageEnglish
Pages (from-to)2690-2697
Number of pages8
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Issue number16
Publication statusPublished - 15 Aug 2009
Externally publishedYes


  • Alkali iodides
  • Defects in solids
  • Indium tin oxide
  • Ion beams
  • Lithium niobate
  • Nanoparticles
  • Optical techniques
  • Silicon

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation


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