Photoassisted tunneling spectroscopy: Preliminary results on tungsten diselenide

In this study we introduce a novel use of the scanning tunneling microscope as an instrument to investigate the local quantum yield of photoelectrons from illuminated semiconductor surfaces. The photoinduced tunneling current resulting from the illumination of the surface with monochromatic light is investigated as a function of the wavelength. Information on the energy dependent creation and recombination of electrons in the vicinity of surfaces are obtained by this method with high spatial resolution without the necessity of covering the surface by a conducting film. Thereby all defects associated with the electrode–semiconductor interface are avoided.