Scanning Near-Field Optical Microscopy and Scanning Thermal Microscopy

Abstract

The development of the scanning tunneling microscopy has led to the development of related techniques which include the scanning near-field microscopy (SNOM) and the scanning thermal microscopy (SThM). These techniques provide sample information in addition to the simultaneously obtained topography. With SNOM normal optical microscopy contrast mechanisms (adsorbance, fluorescence, polarization, etc.) can be used. The principles and design of a SNOM are presented. Subwavelength resolution (better than λ/20) is demonstrated. In SThM, the contrast is provided by temperature and thermal conductivity. The design of a resistive thermal probe is described. Several operating modes are described and image contrast due to thermal conductivity is demonstrated.

Design and construction of a heat stage for investigations of samples by atomic force microscopy above ambient temperatures

“…Contrary to the results obtained with the atomic force SThM [26][27][28][29][30][31] we can obtain atomic resolution with the use of the heat stage described above. The following two features are believed to be important: First, since heat conduction through air represents the major mode of heat transfer between sample and tip, 29 we work the AFM with the cantilever and the sample at thermal equilibrium, which eliminates any major cantilever fluctuations due to thermal drift.…”

“…25 Furthermore, several successful attempts by different authors to convert the AFM into an atomic force SThM by modifying the cantilever have been reported. [26][27][28][29][30][31] In this setup, heating occurs either through the tip 30,31 or by direct sample heating. However, at present the lateral resolution using atomic forces SThM lies on the scale of micrometers with both heating methods, which is in contrast to the atomic resolution obtainable with the tunneling SThM.…”

High density data storage with a SNOM

“…6 The laser power for the reading was 0.2m W in the reflection SNOM with the PC film, while it was 2mW in the transmission SNOM with the MO film. The incident laser power of 0.2mW is equivalent to 0.02 to O.OO2mW in the transmission SNOM, because a solid angle of the objective lens to the tip of the probe is 0.1 to 0.01 and the decrease of transmissivity in the phase change is the same as the increase of reflectivity.…”

“…The features of the SNOM are to have a laser diode illumination system for writing and reading,3.4 a shear force detection for the gap controlS and a reflected light detection for reading. 6 The laser diode (HL 7852G made by Hitachi) has a wavelength of 785nm and a maximum output power of 50mW.7 Through the first Md the second optical couplings, maximum power of 15mW in the SNOM probe was obtained. The SNOM can control constant spacing gap between the probe and the sample using a shear force detector for non-contact atomic force micfQscOpe (AFM) operation.…”

Scanning thermal lithography for nanopatterning of polymers

“…Hence, it was recognized that the use of probes with internal microscale heaters would greatly simplify the operating procedure. In 1994, West and coworkers 77,78 reported on the development of the first probes with an integrated resistive heater. These were made from a Wollaston process wire, consisting of a 5 µm thick platinum core surrounded by a 75 µm silver corona.…”