71P3-17Preparation and Evaluation of a High-temperature Flame-etched Tungsten Tip for Scanning Probe Microscopy Yuta Okabe1, Nobuhiko Utsunomiya2, Yuki Araki2, Masahiko Tomitori3, and Toyoko Arai1,2 1 School of Mathematics and Physics, Kanazawa University 2 Graduate School of Natural Science and Technology, Kanazawa University 3 Japan Advanced Institute of Science and Technology (JAIST) The sharpness and physical-chemical states of a tip for scanning probe microscopy (SPM) are of central concern to obtaining high-resolution SPM images without artifacts, in particular, toward nanoscale materials characterization regarding their electronic properties, because the SPM images stem from a complex interaction occurring between the tip and the sample at the close separations. The atomic arrangements of the tip chiefly govern the mechanical and electronic properties of the tip. Therefore, a single crystalline tip, whose apex is surrounded by stable crystallographic planes, is attractive. Conventional high-temperature (> 2000 °C) flame-etching of a polycrystalline W wire using a 2H2+O2 mixed gas, electrolyzed from pure water, can produce a sharp tungsten (W) tip quickly in less than 1 sec, whose apex is of a few-tens micrometer single crystal domain. However, the surface is covered with tungsten oxides (WOx) after the flame etching. In the present study, we develop a method to remove the oxides while making the tip sharper by following a short-time electrochemical etching at low bias voltages. Furthermore, we also heat the W tip with a high-power blue laser in a vacuum. The tip shape and chemical compositions are analyzed using scanning electron microscopy with Auger electron spectroscopy and transmission electron microscopy with electron diffraction.
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