Beam-induced conductivity

We have thus far reported only to the SE signal as a means of generating an image in the SEM. In fact, several other signals are generated as a result of the interaction of the incident electron beam with the specimen. These include backscattered electrons (BSEs), X-rays, light, heat, specimen current, electron beam induced conductivity, transmitted electrons (if the specimen is thin enough), to name the most commonly used. 

Imaging Modalities. Confocal contrast generation include reflectance, rescattering, and fluorescence. The first results in confocal imaging were obtained on unstained tissue in reflectance [78]. Reflectance is also the preferred imaging modality used in industrial inspection of semiconductors, often combined with methods such as optical beam induced conductivity (OBIC). 

J. Davenas, Influence of the temperature on the ion beam induced conductivity of polyimide, Appl. Surf. 5a. 43 218 (1989). 

Figure 25. One-to-one correspondence between (a) dislocation etch-pit distribution, (b) cathodoluminescence images and (c) electron-beam-induced conductivity images of the same region of a GaP layer (104).

At this stage, the potential of E-beam induced reverse electron transfer in conducting organic charge transfer salts for lithographic applications is unclear. However, these materials do possess a rather unique combination of properties that may be of considerable value in future applications where traditional resist materials may be unsuitable. Some of the key features of these new resists are summarized below ... 

However, the SEM contrast of CNT can be difficult to interpret as it depends on a lot of parameters (76) the primary beam energy landing, the history of imaging, if the CNT are lying on a substrate or suspended, the substrate electrical conductivity and the electron beam induced contamination during imaging. The contrast can for example be linked to potential differences between the CNT and the substrate (77), or to electron beam-induced current on the insulating substrate surface (78). 

This expression establishes a relation between the cross section of ion beam-induced damage of the polymer host and the threshold fluence c. Note that the experimental p values are, generally, somewhat lower thus a percolation threshold of about 0.3 was deduced for polyimide implanted with 500-keV from the conductivity versus filling factor dependence [87]. In general, the following power law dependence of the percolation probability on the implanted dose holds [11,87] ... 

Eskildsen, S. S., and Sdrensen, G., The formation of conductive films on polyimide by ion-beam-induced decomposition of metal compounds, Nucl. Instrum. Methods Phys. Res., B7/8, 481-486 (1985). 

Y.H. Lee, R. Biswas, C.M. Soukoulis, C.Z. Wang, C.T. Chan, K.M. Ho, Molecular-dyntunics simulation of thermal conductivity in amorphous silicon. Phys. Rev. B 43,6573-6580 (1991) L. Pelaz, L.A. Marqus, J. Barbolla, lon-beam-induced amorphization and recrystallization in silicon. J. Appl. Phys. 96, 5947-5976 (2004)... 

Polysulfones are materials of great technological interest due to their applications as polymeric membranes, resists for microelectronics, heat-resistant materials in aerospace applications, matrices for composites, etc. It has been shown that ion beam treatment applied in the low-keV range is a suitable way to modify some relevant properties of polysulfones, such as solubility or electrical conductivity (117, 118], XPS is probably the most suitable analytical method for the characterization of ion-beam-induced changes in the composition and chemical state of polysulfone,s, e.g of aromatic polyfether sulfone) (PEiS) [119, 120). 

Even though the vacuum-oriented surface techniques yield much useful information about the chemistry of a surface, their use is not totally without problems. Hydrated surfaces, for example, are susceptible to dehydration due to the vacuum and localized sample heating induced by x-ray and electron beams. Still, successful studies have been conducted on aquated inorganic salts (3), water on metals (3), and hydrated iron oxide minerals (4). Even aqueous solutions themselves have been studied by x-ray photoelectron spectroscopy (j>). The reader should also remember that even dry samples can sometimes undergo deterioration under the proper circumstances. In most cases, however, alterations in the sample surface can be detected by monitoring the spectra as a function of time of x-ray or electron beam exposure and by a careful, visual inspection of the sample. 

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