Tip-related artifacts in scanning tunneling potentiometry

We show that tip-related artifacts can produce artificially abrupt and/or nonmonotonic behavior in scanning-tunneling-potentiometry (STP) measurements of rough surfaces, and thus considerable care must be used in interpreting actual STP images. Low-noise STP measurements were made on several metal films, and confirm that such artifacts do in some cases exist. These tip artifacts are often more obvious in STP images than in the corresponding topographic images, and hence STP may provide a valuable means to detect the presence of tip artifacts in other scanning-tunneling-microscope experiments. © 1990 The American Physical Society.