Microscopic observation of vacancy and self-interstitial and the formation of Frenkel pairs in InSb by Mossbauer spectroscopy

摘要

The process of Frenkel pair formation in n-InSb is investigated by application of Mossbauer spectroscopy with correlated Frenkel pair production utilizing the Mossbauer probe ~(119)Sb/~(119)Sn as primary knock-on atom (PKA). This is achieved by starting the Mossbauer decay chain on the precursor ~(119g)Te which feeds the "proper" standard probe ~(119)Sb/~(119) Sn and in this process emits a high energy neutrino which leads to 12 eV monoenergetic recoil energy exerted on the Mossbauer probe. Since the defect production threshold in InSb is about 8 eV, single Frenkel pairs consisting of one vacancy and one self-interstitial can be expected. This simplest possible defect creation mechanism indeed enables identification of two single vacancy-probe configurations and the probe as self-interstitial thereby elucidating the mechanism of defect formation itself. The relative intensities of the defect fractions corrected for the radioactive decay show that about 55-60% of the Mossbauer probes are associated with a defect. The probability of producing a probe associated vacancy does not depend on temperature between 4 and 300 K. First experiments searching for a doping dependence indicate that in p-type material the probe associated vacancy fractions are not formed.