Scanning tunneling microscopy studies of carbon overcoats of thin film media

STM (scanning tunneling microscopy) data on carbon overcoats of thin film media are reported. Topographic as well as spectroscopic images showing the derivative of the tunneling current I with respect to the tip-to-surface distance s (dI/ds ) are measured simultaneously. Areas of large dI/ds fluctuations are observed, which are attributed to regions of poor conductivity of the carbon film. These domains of instability become larger at higher tunneling current. Carbon films of better mechanical properties show greater homogeneity in conductivity. Atomic structures are also resolved, showing short-range graphitic order for overcoats of poor durability. Harder films show a totally disordered structure