Dual-oriented thin crystals of molybdenum grown under Ar⁺ ion bombardment

Abstract

Ar⁺ sputtering of an Cu(111) surface while simultaneously supplying Mo atoms is known to induce an oriented growth of Mo thin crystals, or “seed-layers”, on evolving conical Cu protrusions. The seed-layers thus formed are shown to be dual-oriented, or bicrystalline, consisting of columnar crystallites grown homo-epitaxially. The orientation relationship between the two types of crystallites was (100)_I ‖ (111)_II with [001]_I ‖ [110]_II, and this bicrystallinity probably resulted from a non-uniform charge-up of the layers' growth front. As concluded from high-resolution electron microscopy, the Mo(100) stacking is elastically converted into the Mo(111) stacking and vice versa, under the influence of tensile stress. The homo-epitaxy that the seed-layers exhibited is believed to reflect the mutual convertibility of the Mo(100) and (111) stackings.