EVIDENCE FOR A LARGE CORRELATION LENGTH IN SURFACE-ROUGHNESS OF COSI2/SI

We present data on parallel electric transport in thin CoSi2/Si and Si/CoSi2/Si layers from 50 down to 12 angstrom. The data show that the surface roughness must be described by a large correlation length xi, i.e., much larger than k(F)-1, where k(F) is the Fermi wave vector equal to 1 angstrom-1 in CoSi2. This is true whatever the model (Gaussian or exponential) used for the autocorrelation function. For CoSi2/Si and Si/CoSi2/Si films we obtain, respectively, xi = 5 and 8 angstrom in the Gaussian model and 10 and 12 angstrom in the exponential one.