RESTRUCTURING OF THE VICINAL CU(997) SURFACE

We have investigated the surface structure of Cu(111) vicinal surfaces with (111)- and (100)-steps using scanning tunneling microscopy and s canning electron microscopy, While the vicinal surface with (100)-step s displays the expected typical step arrays after ultra-high vacuum (U HV) preparation, the surface with (111)-steps becomes macroscopically rough. Scanning tunneling microscope (STM) images of this surface reve al the presence of {212} racers and triangular tiling structures with a {445} mean orientation. The {212} facets consist of (111) double ste ps and (111) terraces. The triangular tiling structure consists of tri angular shaped (111) terraces which are separated by straight (100) an d zigzag shaped (111)-steps in alternate sequence. It is proposed that the observed structures represent local minima in the free energy of the surface which are more easily accessible than the true equilibrium structure under the kinetic constraints of a large Schwoebel-Ehrlich barrier. (C) 1997 Elsevier Science B.V.