Influence of initial structure and stresses on the kinetics of secondary radiation defect accumulation in epitaxial vanadium films

Regularities of formation of secondary radiation defects and stresses in epitaxial vanadium films irradiated with He+ ions and differing in orientation, crystal structure perfection and elastic strains present in them are investigated using precision x-ray diffractometry, electron microscopy and electric resistance methods. In all the films investigated compressive strains ε∼0.4% are generated under irradiation, after which the secondary defect formation process is suppressed. The effect is linked with increased interstitial atom and vacancy recombination on favourably located defects of dislocation type (introduction loops and edge dislocations). Initial growth of lattice parameter a0 in a non-stressed cross section in perfect films is provided by small introduction loops, and its reduction in imperfect samples-by HeV helium-vacancy complex formation. Further growth of a0 is conditioned by Frenkel pair recombination stresses, and HemVn (m>n) complex enrichment with helium