RADIATION DEFECT STRUCTURE IN SINGLE CRYSTALS. G.N.Eritsian, N.E. Grigorian, A.A. Sahakian, S.K. Nickogosian, Yerevan Physics Institute, 2 Alikhanian Brothers St., Yerevan, 375036, Armenia

Radiation defects formation and their influence on the properties of single crystals, both elementary (Se) and binary (GaP) are examined. The pecularities of Si atom displacement and its movement via the identical atom chains along <110> are discussed in respect to GaP crystals where two sublattices are taken into account. It was shown that the high velocity of interstitual Si atoms causes different defect coagulations with vacancy and impurity atoms. In GaP crystals the defects are almost immovable because the atoms shift to the second coordination sphere.

After irradiation narrowing of the forbidden gap in the crystal has been observed. In Si it has a continous character while in GaP it seems as the "tail" of the charge density states. This effect was explained as an interaction of radiation defects with crystal lattice via the deformation potential [1].

Using synchrotron radiation two new bands at 140 and 146 eV have been obtained in the reflection spectra of irradiated GaP crystals which are attributed to noncontrolled impurity As atom M 2,3 core transitions with spin-orbit splitting of 6 eV.

These effects are discussed in detail in terms of migration of impurity atoms from the bulk to the surface of the crystal under the irradiation [2].

References

1. E.Yu.Brailovskii et al., Izvestii Academii Armenii. Physics, v.18, 235, (1983)

2. N.E.Grigorian, G.N. Eritsian. Phys. Status Solidi (in press)