The effect of ion species on morphological structure development of ion bombarded (1131) single crystal Cu

Abstract

Carefully prepared samples of (1131) oriented Cu single crystals were bombarded with 40 keV ions to fluences of the order of 10 19 cm −2. The ion species chosen were Ne, Ar, Kr, Xe, N and Cu, and thus represented a range of light to heavy, chemically inert species, a more chemically active species and the self ion species. Post-irradiation observation was performed by scanning electron microscopy at Copenhagen and subsequently at Salford. The results may be summarized as follows: 1. (1) All ion species lead to characteristic morphological surface changes including etch pit, and frequently, pyramid generation. 2. (2) The lighter ion species tend to produce lower pit densities and less well-defined pit habits and fewer, sometimes no pyramids. 3. (3) The heavier ions (including Cu +) produce denser arrays of all features and better geometrically defined features. 4. (4) N +, Ne + and Ar + ions produce a zone of surface blisters outside but surrounding the irradiated area but none within the irradiated area. 5. (5) Some signs of pyramid bending occur from one to a subsequent examination but there are no clear correlations with ion species and surface zone. 6. (6) The as-formed pyramids are in dense crystallographic array after Cu, Kr and Xe irradiation. These results are explained in terms of preferential sputtering of native and irradiation induced defect structures and differential atomic mobility of different ion species in the Cu. The Cu + irradiation results exhibit the lack of necessity of occluded gas for feature development whilst the N + results indicate that, for Cu, improved impurity depth profiling accuracy by sputter sectioning with such a chemically active species is unlikely.