Scanning tunneling optical spectrometer

摘要

A scanning tunneling optical spectrometer, and corresponding method, for measuring spectral response of a tunneling probe-sample junction over the range of optical frequencies enabling determination of characteristics of and imaging of subsurface structures with nanometer resolutions. A tunneling probe is positioned adjacent the sample with a bias voltage applied and an optical source is employed to direct modulated optical radiation onto the sample probe junction to generate photoexcited tunneling current without interference from tunneling current variations caused by thermal heating by the optical radiation. The optical source is frequency scanned over a selected frequency range and the photoexcited tunneling current is detected employing phase detection thereby permitting measurement of properties of such materials as semiconductors, buried semiconductor structures, and other organic or inorganic photoconductors. Scanning tunneling optical microscopy is provided by scanning the surface of the sample thereby permitting imaging of subsurface structures.