Direct observation of a beta-SiC(100)-c(4x2) surface reconstruction

We provide the first direct observation of a beta-SiC(100)-c(4 X 2) surface reconstruction. The experiments are performed using high-resolution scanning tunneling microscopy (STM). Flat surfaces having a long range order are grown. Individual Si dimers are identified and form a centered pseudohexagonal pattern give a c(4 X 2) array. Further support for Si-dimer identification is provided by theoretical STM image calculations. The results suggest a model of dimer rows having alternatively up and down dimers (AUDD) within the row, in an ''undulating'' type of arrangement reducing the surface stress. Hence the beta-SiC(100)- and Si(100)-c(4 X 2) surface reconstructions are very different.