Low-energy electron diffraction and photoemission study of epitaxial films of Cu on Ag{001}

The epitaxy of Cu on Ag{001} is studied by qualitative and quantitative low-energy electron diffraction (LEED) and by angle-resolved photoemission. LEED indicates that ultrathin (two- to three-atomic-layer) films have a limited amount of long-range order, and the ordered component has interlayer spacings of 1.45±{}0.06 {}, which compares well with the theoretically determined cubic lattice constant 2.87±{}0.06 {} of a metastable body-centered-cubic (bcc) modification of Cu. Thicker (10- to 12-layer) films have almost no long-range order, and photoemission indicates that regions of bcc and fcc Cu coexist amid large amounts of defects.