# Open Question to Point Defects Von G.F. Cerofolini (1989): `Having recently written a book on physical chemistry of, in and on silicon [1], I have considered some of the most obvious queries which could be raised when considering such a topic, viz.:` `which is the atomic configuration of point defects? (e.g., is the self- interstitial quasi free or does it have a dumb-bell configuration?)` `has each defect only one configuration or are several configurations possible?` `which is the electronic structure?` `which charge states are associated with each defect and where are they located in the gap?` `can the defect be actually considered pointlike (i.e., do the remaining atoms remain on their lattice location) or does the deformation extend to long range?` `does an entropic or enthalpic barrier exist for Frenkel-pair recombination?` `which are the defect diffusivities in relation to their charge states?` `is the surface an effective generation-recombination centre for point defects?` `to which extent does this generation-recombination rate depend on surface conditions (free, oxidated, nitridated, etc.)?` `Most of them, however, remained unanswered.`

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1.3.2 Materials Properties and Defects

1.3.3 The larger View and Complications

© H. Föll (Defects - Script)