Scaling behavior of (0 0 1) and (1 1 1) Cu surfaces

Single crystalline Cu films are extensively used as buffer layers for a variety of applications. Cu films can be grown epitaxially on hydrogen-terminated Si(0 0 1) and (7×7) reconstructed Si(1 1 1) substrates but the ultimate surface of the “as-grown” films tends to be quite rough. For most applications this constitutes a technical drawback. Using correlated reflection high-energy electron diffraction (RHEED) and STM data, we have found a dramatic smoothing of epitaxial Cu(0 0 1) surfaces by annealing the as-grown films in the 120–160 °C temperature range and somewhat less so for the Cu(1 1 1) films. Scaling analysis of the subsequent Cu growth on the annealed smooth surfaces yields a coarsening exponent of one-fourth for the (0 0 1) oriented films while this exponent is one-third for the (1 1 1) films, providing experimental data for a comparison of the same system film–substrate in these two orientations.