Photon scanning tunneling microscope using diode lasers

Abstract

A novel superresolution photon scanning tunneling microscope (PSTM) using diode lasers and optical fibers has measured a submicron structure sample in a noncontact and nondestructive manner. Diode lasers, which can be directly high speed modulated, are used to make the system more compact (25 × 20 × 12 cm3) and the measuring time shorter. The principle of the operation is that the evanescent flied (tunneling photon) depending on the topography of the sample is picked up by a fiber probe on which the subwavelength aperture is fabricated. The top of the fiber probe was sharpened by HF selective etching to achieve 80-nm radius of curvature. A stepped SiO2 thin film 9 nm high optical disk with submicron sized pits similar to a moth-eye structure was observed. Furthermore, 80-nm diameter latex particles have also been observed. These are the smallest size particle resolved by the PSTM, to the author’s knowledge. A reflection-resonance type PSTM is proposed1 for solving the problem with the low power picked up in a transmissiontype PSTM (demonstrated above), which limits the measurement sensitivity.