INFLUENCE OF A TIP/SAMPLE INTERACTION ON SCANNING TUNNELING SPECTROSCOPY DATA

Abstract

The electronic states and the tunnel current for the W/Si and W/Al tip/sample systems were calculated by the first-principles discrete-variational method of the local-density approximation. It was found that the local-electronic structure of the Si surface resembles that of a free sample even for the tip/sample distances of 2–3 Å. The electronic structure of the Al surface is more sensitive to the tip/sample interaction and approaches the free surface form when the tip/sample distance is larger than 4 Å. The local density of states of the W tip also depends on the tip/sample distance and must be taken into account in the tunnel-current calculations and in the interpretations of the STS data.