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Apr 1999

Volume 70, Issue 4, pp. 1907-2179

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back to top MICROSCOPY and IMAGING

Laser scanning microscope for low temperature single molecule and microscale spectroscopy based on gradient index optics

Martin Vácha, Hiroshi Yokoyama, Takashi Tokizaki, Makoto Furuki, and Toshiro Tani

Rev. Sci. Instrum. 70, 2041 (1999); http://dx.doi.org/10.1063/1.1149707 (5 pages) | Cited 10 times

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A scanning optical microscope for low temperature imaging and spectroscopy with a gradient index rod-shaped microlens as an objective lens is presented. The solid immersion effect enhances the resolution to 310 nm of the full-width at half-maximum at the wavelength of 545 nm. Laser scanning mechanism located outside an optical cryostat enables to achieve large scanning ranges independent of temperature. The performance is demonstrated at 1.6 K on single molecules of terrylene in a dodecane crystal and on molecular J aggregates in thin polymer films. © 1999 American Institute of Physics.
Show PACS
07.60.Pb Conventional optical microscopes
42.79.Ry Gradient-index (GRIN) devices
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
87.64.M- Optical microscopy
42.79.Bh Lenses, prisms and mirrors
87.64.K- Spectroscopy
42.30.Va Image forming and processing

Novel thin membrane probe and a new twisting modulation force detection method of an atomic force microscope

Katsushi Nakano and Yoshihiko Suzuki

Rev. Sci. Instrum. 70, 2046 (1999); http://dx.doi.org/10.1063/1.1149708 (3 pages) | Cited 1 time

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For inspection of high aspect ratio structures like narrow semiconductor trenches, a thin membrane probe and a new force detection method have been proposed. Instead of conventional conical and pyramidal tips, a thin silicon nitride cantilever was set up vertically, and its edge was used as a tip. The membrane probe named as twist-probe (TP) was oscillated in the twisting resonance to detect a force from both vertical and lateral directions. About 100 μm long, 0.7 μm thick TP was fabricated as a trial. Amplitude versus distance curve measurements showed that the TP has a high spacing change sensitivity between the tip and a sample in both vertical and lateral directions. A trench cross-section imaging was demonstrated successfully with a TP and the twist resonant force detection method. © 1999 American Institute of Physics.
Show PACS
07.79.Lh Atomic force microscopes
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy
07.10.Cm Micromechanical devices and systems
85.30.De Semiconductor-device characterization, design, and modeling
07.10.Pz Instruments for strain, force, and torque
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices

A circuit for measuring the gap voltage of a scanning tunneling microscope on a nanosecond time scale

M. Ochmann, H.-J. Münzer, J. Boneberg, and P. Leiderer

Rev. Sci. Instrum. 70, 2049 (1999); http://dx.doi.org/10.1063/1.1149709 (4 pages) | Cited 3 times

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We demonstrate a new circuit design for fast measurements of the voltage drop across the gap of a scanning tunneling microscope (STM) based on the simultaneous operation of two different amplifiers. The first is a fast instrumentation amplifier, sensing directly the voltage drop across the tunneling barrier, the second is a medium speed current amplifier with an overall gain of 108 V/A, suitable for normal STM operation. We obtained a time resolution of 10 ns measuring the plasma ignition under a STM tip during illumination with an intense 10 ns laser pulse. Possible applications include the study of STM point contacts. © 1999 American Institute of Physics.
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07.79.Cz Scanning tunneling microscopes
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
84.30.Le Amplifiers
07.68.+m Photography, photographic instruments; xerography

Tracking and stepping control of the tip position of a scanning tunneling microscope by referring to atomic points and arrays on a regular crystalline surface

Masato Aketagawa, Koji Takada, Yoshihisa Minao, Yuki Oka, and Jong-Doo Lee

Rev. Sci. Instrum. 70, 2053 (1999); http://dx.doi.org/10.1063/1.1149710 (7 pages) | Cited 7 times

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In this article tracking and stepping control of the tip position of a scanning tunneling microscope (STM) by referring to atomic points and arrays on a regular crystalline surface which is used as a two-dimensional reference scale is described. Highly oriented pyrolytic graphite (HOPG) crystal, whose lattice spacing is approximately 0.25 nm, was used as the reference. To utilize the topographic features on the crystalline surface as a reference, a method for determining two-dimensional lateral gradient signals, i.e., the X, and Y axes gradient signals, of the crystalline surface was applied to the control. A rigid STM consisting of a tip scanner and a sample XY stage, and control instruments were developed. The X and Y axes gradient signals were obtained simultaneously using two-phase lock-in modulations of a tunneling current modulated with circular dither motion applied to the tip XY scanner. Modulation frequency and amplitude of the tip were 1 kHz and less than 0.04 nm, respectively. The sample XY stage was controlled for tip positioning by feedback of the X and Y axis gradient signals. First, the tracking control of the STM tip onto an atomic point of the HOPG surface for a maximum duration of about 10 min was performed. Second, tracking and motion control of the STM tip along a crystalline axis of the HOPG surface was demonstrated. The STM tip continued “back and forth” motion along the crystalline axis of the HOPG surface for a maximum duration of 200 s with a maximum tip speed of 6 nm/s. The maximum displacement deviation from the crystalline axis was less than 1/3 lattice spacing (∼0.08 nm). Third, the quantized stepping of the STM tip with lattice spacing stepping with a repetitive rate of 0.5 Hz along the crystalline axis was examined. The maximum displacement deviation from the crystalline axis was less than 1/2 lattice spacing (∼0.12 nm). The feasibility of tracking and stepping control of the STM tip position by referring to atomic points and arrays was confirmed, and the proposed method can be applied to real-time length measurement with subnanometer resolution using a regular crystalline lattice. © 1999 American Institute of Physics.
Show PACS
07.79.Cz Scanning tunneling microscopes
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy
68.35.B- Structure of clean surfaces (and surface reconstruction)
07.07.Tw Servo and control equipment; robots
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