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New Insights into Subsurface Imaging of Carbon Nanotubes in Polymer Composites via Scanning Electron Microscopy



Minhua Zhao, Bin Ming, Jae-Woo Kim, Luke J. Gibbons, Xiaohong Gu, Tinh Nguyen, Cheol Park, Peter T. Lillehei, John S. Villarrubia, Andras Vladar, James A. Liddle


Despite many studies of subsurface imaging of carbon nanotube (CNT)-polymer composites via scanning electron microscopy (SEM), significant controversy exists concerning the imaging depth and contrast mechanisms. We studied CNT-polyimide composites and, by three dimensional reconstructions of captured stereo-pair images, determined that the maximum SEM imaging depth is typically hundreds of nanometers. The contrast mechanisms were investigated over a broad range of beam accelerating voltages from 0.3 kV to 30 kV, and ascribed to modulation by embedded CNTs of the effective secondary electron (SE) emission yield at the polymer surface. This modulation of the SE yield is due to non-uniform surface potential distribution resulting from current flows due to leakage and electron beam induced conductivity (EBIC). The importance of an external electric field on SEM subsurface imaging was also demonstrated. The insights gained from this study can be generally applied to SEM subsurface imaging of conducting nanostructures embedded in dielectric matrices (i.e., non-destructive imaging of graphene-polymer composites, silicon-based single electron transistors, SEM overlay metrology or e-beam lithography) and have significant implications in nanotechnology.


carbon nanotube, polymer composites, subsurface imaging, scanning electron microscopy, contrast mechanism, surface potential, electron beam induced conductivity (EBIC), Monte Carlo simulation, electric field, focused ion beam.


Zhao, M. , Ming, B. , Kim, J. , Gibbons, L. , Gu, X. , Nguyen, T. , Park, C. , Lillehei, P. , Villarrubia, J. , Vladar, A. and Liddle, J. (2015), New Insights into Subsurface Imaging of Carbon Nanotubes in Polymer Composites via Scanning Electron Microscopy, Nanotechnology, [online], (Accessed April 16, 2024)
Created February 4, 2015, Updated November 10, 2018