Thickness-Dependent Phase Transformations in Implanted Iron

摘要

The dependence of iron nitride formation and phase transformations on the thickness of the nitrogen implanted Fe layers is investigated. The iron nitrides formation in N-implanted Fe-layers of various thickness (60― 860 nm) implanted with 100 keV N_2~+ ions with doses ranging from 1 x 10~(17) to 4.5 x 10~(17) at. N/cm~2 is studied by CEMS and supplemented by GXRD. It was found that nitride formation is strongly enhanced in thin Fe films as compared to thicker layers or the bulk samples. A given nitride phase is formed in thin (60, 130 nm) Fe layers at significantly lower N-doses and the transformation of the original Fe layer into iron nitrides is more complete than in the bulk α-Fe. It is suggested that high stresses in thin Fe layers, revealed by the GXRD measurements, may enhance nitrides formation.