AbstractLight detection system combined with a UHV-scanning tunneling microscope (STM) was applied to the study of silver films deposited on Si(111) surfaces. Photon maps clearly show single atom height steps and terraces on an Ag(111) surface with high spatial resolution of nanometer scale. Chemical reaction on the Ag surface with residual gas was clearly revealed in the photon map. In the photon map of the thin Ag film of 2˜3 ML in thick, no contrast appears between the terraces, and a characteristic bright contrast appears at the single atom height steps. The local plasmon model does not readily explain those contrasts.
AbstractVisible light is emitted when electrons (holes) are injected into a sample from the tip of the scanning tunneling microscope (STM). By analyzing the spectra of the emitted light, one can not only determine the surface geometry by usual STM imaging, but also learn the electronic and optical properties of specific individual nanostructures. This technique has been applied to investigate the electronic transitions of individual protrusions of porous Si and semiconductor quantum wells of AlGaAs/GaAs. The usefulness, limitations, and future expectations of this novel technique are discussed.