X-ray nanotomography of SiO₂-coated Pt₉₀Ir₁₀tips with sub-micron conducting apex

Abstract

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Synchrotron X‐Ray Scanning Tunneling Microscopy: Fingerprinting Near to Far Field Transitions on Cu(111) Induced by Synchrotron Radiation

“…Figure shows a scanning electron micrograph of a PtIr tip, which is entirely coated by a 500‐nm‐thick insulating SiO 2 film except at the apex. The coated tip with sub‐micron conducting apex was prepared by means of electron beam physical vapor deposition, focused ion beam milling, and subsequent ion beam stimulated oxide growth 20. The coating confines the detection of photoejected electrons to a small area at the tip apex.…”

“…Chemical contrast with a spatial resolution of about 10 nm has already been reported 16, 17. It is expected that the spatial resolution can be further enhanced by means of special insulator coated tips with a minimized conducting apex, which avoid the exposure of the sidewall of the tip to photoejected electrons 18–20. However, to achieve ultimate resolution it will be critical to maintain stable tunneling conditions during X‐ray excitation.…”

Hard X-ray beam damage study of monolayer Ni islands using SX-STM

“…Because photoejected electrons from the sample can interfere with the conventional tunneling conditions of the STM [15], a nanofabricated "smart tip" was utilized, covered with layers of insulating and conductive coatings [12]. The smart tip focuses electron detection solely near the apex region of the scanning tip where the main interaction with the sample occurs, minimizing the background electrons collected at the sidewalls of the tip [16,17]. Additionally, the incoming X-ray beam was chopped at 3 kHz in order to achieve stable tunneling conditions through a filter that separates photoexcited currents from the topographic signal used in the feedback system of the STM [18].…”

Spin-dependent synchrotron x-ray excitations studied by scanning tunneling microscopy

“…Thus, it is critical to utilize insulator-coated tips with a small conducting apex. [13][14][15] In this paper, we demonstrate the spin-dependent detection of photoejected electrons by an insulator-coated tip in the far field. Utilizing the polarization and energy tunability of synchrotron x-rays, chemical and magnetic information can be deduced from the tip current.…”