THE ROUGHENING OF METAL-SURFACES

We address the problem of the departure of a crystal surface from a pe rfectly ordered crystal plane. We discuss the energetics of the surfac e defects and their statistical mechanics which lead to the so-called ''roughening transition''. The theory of this transition is outlined a nd a special emphasis is put on the experimental aspects: roughening m easurement techniques and critical review of the available data. We pa y special attention to the case of vicinal surfaces. Apart from the eq uilibrium situation there is an increasing interest in the dynamical r oughening of crystal surfaces during MBE growth or ion-bombardment etc hing, or in the reverse problem: the annealing of a non-equilibrium ro ughness. We review the present state of this field by recalling releva nt models which lead to the concept of dynamical scaling and we discus s some recent data. The present review is restricted to the case of me tal surfaces; however, most of the concepts which are presented have a much larger generality.