Detection of Au⁺ Ions During Fluorine Gas-Assisted Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) for the Complete Elemental Characterization of Microbatteries

Abstract

Due to excellent electric conductivity and chemical inertness, Au can be used in new microdevices for energy applications, microelectronics, and biomedical solutions. However, the chemical analysis of Aucontaining systems using time-of-flight secondary ion mass spectrometry (TOF-SIMS) can be difficult because of the negative ionization of Au, as most metals form positive ions, and therefore cannot be detected from the same analytical volume. In this work, we present the potential of fluorine gas coinjection for altering the polarity, from the negative to positive, of Au secondary ions generated under Ga + beam bombardment. The importance of detecting Au + ions and representing their spatial distribution in nanoscale was demonstrated using a novel solid electrolyte for Li-ion solid-state batteries, amorphous Li 7 La 3 Zr 2 O 12 (aLLZO). This allowed for assessing the migration of mobile Li + ions outside the aLLZO layer and alloying the Au layer with Li, which explained the presence of an internal electric field observed during the polarization measurements. Remarkably, during fluorine gas-assisted TOF-SIMS measurements, the trace amount of Au content (5 ppm) was detected in a Pt layer (unattainable under standard vacuum conditions). In conclusion, fluorine gas-assisted TOF-SIMS can help understanding operation mechanisms and potential degradation processes of microdevices and therefore help optimizing their functionality.

3D High-Resolution Chemical Characterization of Sputtered Li-Rich NMC811 Thin Films Using TOF-SIMS

“…This statement is supported by studies on Au-containing systems. 6 A span of the passivation layer was estimated to be approx. 39 frames (2 min 3 s of sputtering time) based on the secondary-ion distributions of Ni, Mn, and Co (the location of approx.…”

“…However, they do not provide any information on the sample's chemical or morphological structure, meaning that the operation mechanisms and potential degradation cannot be assessed. 6 Although X-ray computed nanotomography allows the morphological structure of relatively large specimens (tens of microns) 7 to be obtained with a high spatial resolution (below 50 nm), its application for imaging Li can be difficult due to the low attenuation coefficient of Li, resulting in limited X-ray absorption contrast. 8 Therefore, for example, the distinction between Li metal and submicron voids in SSE is not trivial.…”

“…However, during a single measurement, only either positive or negative ions can be guided toward a mass analyzer and therefore be measured. In conjunction with the destructive nature of this method, this means that the information on elements dominantly generating positive ions cannot be directly correlated with the information on the elements, which dominantly ionize with the negative charge from the exact same volume (unless fluorine gas assistance is provided 6 ). During the data acquisition (Figure S1 in the Supporting Information), a primary-ion beam scans a sample surface pixel by pixel and frame by frame (1 frame = 3.17 s in this case).…”

“…More information about the data processing as well as the comparison between the HVcompatible TOF-SIMS add-on to FIB/scanning electron microscope and standalone dedicated TOF-SIMS instruments operating under ultra-HV (UHV) can be found in our previous publications. 6,28 The TOF-SIMS data were acquired in the positive-ion detection mode at 20 keV beam energy, ensuring high lateral and depth resolutions. 111−112 pA ion current, 12 μs dwell time, and a 90 μm aperture were used.…”

Real-Time In Situ Parallel Detection of Elements and Molecules with TOFMS during ALD for Chemical Quality Control of Thin Films

“…Furthermore, several post-mortem chemical characterization techniques, such as time-of-flight secondary ion mass spectrometry (TOF-SIMS), , scanning transmission electron microscopy combined with energy-dispersive x-ray spectroscopy (STEM/EDX). as well as atom probe tomography (APT), can provide information on chemical structure of deposited thin films in 3D with nanoscale resolution. − The nanometric depth resolution can be also reached with X-ray photoelectron spectroscopy (XPS), but in this case the lateral resolution is in the order of several micrometers . However, information on chemical reactions and chemical byproducts, which occur from the surface reactions between the solid substrates and gas precursors, is much more challenging to assess.…”