In-situ reflection high-energy electron diffraction study of epitaxial growth of Cu on NaCl (100) under oblique angle vapor deposition

Epitaxial growth of copper on annealed NaCl(100) surface was carried out using thermal evaporation at an oblique angle of incidence (75 ± 5)° with respect to the substrate normal. The substrate was kept at a temperature of (150 ± 5)°C. The crystalline structure of the Cu film was studied in situ by reflection high energy electron diffraction at various deposition times. We observed that the film grows through nucleation of epitaxial islands followed by coalescence and then flattening of the film. The chevron shaped diffraction patterns formed by the refraction effect of electrons were used to identify the crystal facets. With longer deposition times, instead of columnar structures, a continuous epitaxial film was formed despite the oblique angle incidence of the vapor. The morphology of the final film was characterized ex situ by atomic force microscopy and shows L-shaped pores asymmetric with respect to the vapor incident direction.