STM measurement of current–potential curves at a semiconductor surface

Abstract

A new experimental method for the analysis of current–potential curves determined with a scanning tunneling microscope in an electrochemical cell is described. Spectroscopic measurements have been performed in sulfuric acid at a tungsten diselenide semiconductor sample. Measurements of current–voltage curves obtained with the STM for different tunneling gaps and for different potentials of the tip and the semiconductor are recorded, and results are shown. Current–distance curves obtained from these measurements allow the separation of the influence of the tunneling barrier from that of the Schottky barrier at the semiconductor/electrolyte interface. Changes in the barrier heights are due to an electronic influence from the tip potential on the semiconductor surface potential when the tip enters the electrochemical double layer.