Development of Nanoscale Laser Spectroscopy Based on Photon STM for the Study of Semiconductor Mesoscopic Systems

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The aim of this project is to ascertain the validity of photon STM (Scanning Near-field Optical Microscope, SNOM) by making AFM/SNOM instruments with cantilever-type optical fiber probe, which can be used in vacuum and also at low temperature. As a typical sample for SNOM measurement, we have adopted the layr of polystirene particles (LATEX) which are self-organized two-dimensionally on a glass plate.1) Transmission and luminescence excitation images of LATEX layrs by the use of the illumination mode have been measured. Electromagnetic waves propagating both along and perpendicular to the layr plane with some preferable propagation directions are observed. The SNOM images are found to be dependent on the wavelength of the laser light and expected to reveal some properties about photonic band effect in this 2D periodic material. The same images are found both in the illumination and the collection modes for the optical probe operation and the time-reversal theorem in this system has been discussed together with theoretical expectation.2) For atomic force detection, we have applied tuning fork technique without suffering from a stray light coming from the laser used for sensing the fiber vibration. Clear images similar to the conventional one are obtained and the quartz detection is found to work at very low temperatures in vacuum.3) SNOM images of assembled semiconductor nanoparticles with photon energy at some electronic resonance condition have been theoretically investigated under the scheme of nonlocal optical response theory by taking into account both the resonant and nonresonant contributions of the induced polarization. The SNOM images are found to be dependent on the operation modes of the fiber probe due to the configuration resonance effect.These results demonstrate the validity of the photon STM (SNOM) for the optical measurement of single or assembled nanoparticles of semiconductors in submicrometer scale.