Step fluctuations and step interactions on Mo(0 1 1)

Step fluctuations have been studied on Mo(0 1 1) thin single crystal films with various orientations of miscut, in order to determine the step stiffnesses. Effects of unseen defect structures were clearly visible in some data. Measurements of fluctuation amplitudes and relaxation times were made in the temperature range 1100–1680 K. The results show an anisotropic stiffness of about 0.36 eV/nm along [0 1̄ 1] and about 0.15 eV/nm along [1 0 0]. No temperature dependence of the stiffness was detected. The step free energies derived from the stiffnesses average about 0.27 eV/nm and are less anisotropic by about a factor 3. From the temperature dependence of the relaxation rates, an activation energy of 0.8 ± 0.2 eV was determined for the mass diffusion of the mobile defects responsible for the fluctuations. An appendix details an investigation of correlations induced in the motions of neighboring steps by diffusion and by energetic interactions.