Microwave-induced nucleation of conducting graphitic domains on silicon carbide surfaces

Abstract

Microwave irradiation of the C-rich (0001¯) surface of 6H-SiC is seen to rapidly induce the nucleation of conductive nanoscopic graphitic grains. Discrete graphitic islands are observed and Raman spectroscopy suggests turbostratic stacking with minimal electronic coupling between adjacent graphene layers. Ensemble Raman and near-edge x-ray absorption fine structure (NEXAFS) spectroscopies are used in conjunction with spatially resolved atomic force microscopy, scanning Kelvin probe microscopy (SKPM), and colocalized Raman imaging to characterize the topography and electronic structure of the obtained graphitic domains and to develop a mechanistic description of the nucleation process. SKPM provides a direct spatially resolved means to differentiate conductive graphitic grains from the wide-bandgap SiC semiconductor. NEXAFS spectroscopy allows for evaluation of the planar alignment of the graphitic nuclei. The microwave processing method demonstrated here provides a facile route to patterning conductive domains on a ceramic component for applications in power electronics and multilayered ceramic capacitors.

Probing Nanoscale Chemical Segregation and Surface Properties of Antifouling Hybrid Xerogel Films

“…Images were recorded by using a 50 nm × 50 nm pixel spacing at 0.5 Hz. Frequency-modulated (FM) SKPM was performed with a 3.0 V applied bias and a 10 nm lift providing CPD and CF signals. , …”

“…While the AF properties and efficacy of hybrid xerogel coatings have been established in field studies, their characterization has lagged, relying primarily on atomic force microscopy (AFM) and Fourier transform infrared (FTIR) microscopy. , These methods, although sufficient for some materials, provide limited detail on chemical heterogeneity across smaller length scales because of the limited spatial resolution of traditional FTIR imaging (∼4 μm) and the lack of true colocalization. By comparison, colocalized scanning probe and Raman microscopy measurements offer a significant advantage in spatial resolution (approximately an order of magnitude in a diffraction limited configuration) and provide information to better correlate and “map” chemical and physical characteristics. − These advantages have previously been exploited to characterize nanomaterials , and biological samples, , but there have yet to be any reports using these powerful tools on AF materials.…”

“…By comparison, colocalized scanning probe and Raman microscopy measurements offer a significant advantage in spatial resolution (approximately an order of magnitude in a diffraction limited configuration) and provide information to better correlate and "map" chemical and physical characteristics. 24−26 These advantages have previously been exploited to characterize nanomaterials 27,28 and biological samples, 29,30 but there have yet to be any reports using these powerful tools on AF materials.…”

Hybrid AFM for Nanoscale Physicochemical Characterization: Recent Development and Emerging Applications

“…Raman measurements are made on the same sample spot as the AFM images and are acquired by translating the sample with a high‐accuracy positioning stage to ensure the high performance of both systems. Even though the spatial resolution of analysis is still diffraction‐limited, the co‐localized AFM‐Raman instrument has been used to study the material properties in different research fields such as semiconductors, graphene, carbon nanotubes, polycrystals and epoxy compound …”

Hyperspectral Imaging Microscopy of Acetaminophen Adsorbed on Multiwalled Carbon Nanotubes

“…Enhanced dark-field microscope equipped with hyperspectral imaging (ED-HSI) is superior to the regular optical microscopes in the detection and characterization of engineered nanoparticles in environmental systems. , By combining spectrophotometry and high-resolution imaging, ED-HSI collects spectra of reference materials with known components (e.g., pure AAP) and correlates the reference spectra with a target material (e.g., AAP/CNT mixture) to generate a hyperspectral image and identify specific components of interest in the aqueous samples. , Lately, ED-HSI has been utilized in various studies for tracking nanomaterials, such as silver, gold, and single walled CNTs (SWCNTs). ,− Besides, atomic force microscopy (AFM) with Raman spectroscopy (AFM–Raman) has increasingly been used to study semiconductors, graphene, CNTs, polycrystals and epoxy compound. − The integration of AFM with Raman spectrometry examines samples by a specific shuttle stage that allows transferring the sample from the AFM stage to the Raman microscope stage, and reciprocally. This colocalization technique offers a unique combination of acquiring the physical properties and chemical composition for samples at the same location with submicron spatial resolution. , …”