Experimental investigation of criteria for thermal roughening

The morphology of single domain Si(001)2 × 1 surfaces has been investigated with scanning tunneling microscopy (STM). Using the model of Villain, Grempel and Lapujoulade, which is based on the microscopic properties of the surface, this vicinal surface is found to be thermally rough. On macroscopic scale, however, we did not observe any indication for the expected characteristic logarithmic divergence of the surface height-height correlation function. Possible causes for this discrepancy are discussed briefly