Analytical transmission electron microscopy (TEM) and scanning
electron microscopy (SEM) have been applied for the characterization of
evolution, lateral arrangements, orientations, and the microscopic nature
of nanostructures formed during the early stages of ultrahigh vacuum
electron beam evaporation of Cu onto surfaces of VSe2 layered
crystals. Linear nanostructure of relatively large lateral dimension
(100–500 nm) and networks of smaller nanostructures (lateral
dimension: 15–30 nm; mesh sizes: 500–2000 nm) are subsequently
formed on the substrate surfaces. Both types of nanostructures are not Cu
nanowires but are composed of two strands of crystalline substrate
material elevating above the substrate surface. For the large
nanostructures a symmetric roof structure with an inclination angle of
∼30° with respect to the substrate surface could be deduced from
detailed diffraction contrast experiments. In addition to the
nanostructure networks a thin layer of a Cu-VSe2 intercalation
phase of 3R polytype is observed at the substrate surface. A dense network
of interface dislocations indicates that the phase formation is
accompanied by in-plane strain. We present a model that explains the
formation of large and small nanostructures as consequences of compressive
layer strains that are relaxed by the formation of rooflike
nanostructures, finally evolving into the observed networks with
increasing deposition time. The dominating contributions to the
compressive layer strains are considered to be an electronic charge
transfer from the Cu adsorbate to the substrate and the formation of a
Cu-VSe2 intercalation compound in a thin surface layer.