Making Sense of Complex Carbon and Metal/Carbon Systems by Secondary Electron Hyperspectral Imaging

Abstract

Carbon and carbon/metal systems with a multitude of functionalities are ubiquitous in new technologies but understanding on the nanoscale remains elusive due to their affinity for interaction with their environment and limitations in available characterization techniques. This paper introduces a spectroscopic technique and demonstrates its capacity to reveal chemical variations of carbon. The effectiveness of this approach is validated experimentally through spatially averaging spectroscopic techniques and using Monte Carlo modeling. Characteristic spectra shapes and peak positions for varying contributions of sp2‐like or sp3‐like bond types and amorphous hydrogenated carbon are reported under circumstances which might be observed on highly oriented pyrolytic graphite (HOPG) surfaces as a result of air or electron beam exposure. The spectral features identified above are then used to identify the different forms of carbon present within the metallic films deposited from reactive organometallic inks. While spectra for metals is obtained in dedicated surface science instrumentation, the complex relations between carbon and metal species is only revealed by secondary electron (SE) spectroscopy and SE hyperspectral imaging obtained in a state‐of‐the‐art scanning electron microscope (SEM). This work reveals the inhomogeneous incorporation of carbon on the nanoscale but also uncovers a link between local orientation of metallic components and carbon form.

Understanding Surface Modifications Induced via Argon Plasma Treatment through Secondary Electron Hyperspectral Imaging

“…[ 9 ] As SEHI is carried out in the SEM, local variation in chemical changes and sample topography can be assessed in one step. [ 10 ] To do this, SEHI constructs a series of images of the sample area, where each image is formed from a selected SE energy band. While innovative synchronized structural and chemical characterization of materials by SEHI has many uses, this study focuses on revealing and mapping the spatial variation of functional groups that are affected by Ar plasma treatment through identifying specific energy bands for CH, OH, and CO groups.…”

Characterizing Cross‐Linking Within Polymeric Biomaterials in the SEM by Secondary Electron Hyperspectral Imaging

“…Therefore, the absence of this peak in the observed results is a strong indication of the successful process of crosslinking and shows that polymerization is complete. Abrams et al [23] have shown by the results of an electron beam contamination study that amorphous contamination (hydrogenated carbon) deposits on carbon-based samples can be identified through energy peaks within the 3.3-4.7 eV range. PGS-M photocured polymers show an increase of CH vibrations, specifically CH alkyl, which is associated with the cross-linking of PGS-M after photo-polymerization.…”

Monitoring Carbon in Electron and Ion Beam Deposition within FIB-SEM

“…Expected SE emission differences between the two SES plots appear in the peak intensities previously identified as sp 2 and sp 3 carbon bonding [ 27 , 30 , 35 ]. This initial baseline SES collected is useful not only to monitor carbon, but also to understand the cleanliness of an SEM chamber and what forms of contaminant are present.…”

“…This initial baseline SES collected is useful not only to monitor carbon, but also to understand the cleanliness of an SEM chamber and what forms of contaminant are present. As previous studies have shown, emission in the sp 2 energy range, an amorphous carbon contamination (ACC) region in HOPG, is an indication of EBID related contamination found within the SEM chamber [ 30 , 36 ]. Surface contamination forms will be influenced and characterised by the different chamber environments that occur in the two microscopes.…”

“…From the SEHI stack, SE spectra (SES) can be derived or specific energy ranges utilised to compile surface chemistry maps down to the nanoscale. Diverse applications including chemically mapping semi-crystalline polymers, identifying nanostructure variations within natural materials, and molecular orientation analysis of organic electronic devices, have all demonstrated the benefits of the SEHI chemical mapping [ 27 , 29 , 30 , 31 ]. Carbon EBID has previously been investigated using SEHI [ 30 ], but IBID has not had the same level of analysis applied.…”