부산대학교 도서관

Lay description In the scanning electron microscope (SEM) a focused electron beam is scanned across the surface of a sample. The incident electrons interact with the sample and generate various signals that can be detected. The charged nature of the incident electrons makes the investigation and characterization of insulating samples challenging, as insulating materials do not provide a path to ground (Goldstein et al. 2007). The accumulation of charge is evident as abnormal contrast, image drift and image distortions (Okai, Yano and Sohda 2011). In previous work we have seen that sample charging in arrays of metal nanoparticles on glass substrates leads to a 'shrinkage effect', induced by the imbalance in the number of incident and emitted electrons, resulting in a measurement error in the nanoparticle dimension of up to 15 % (Greve, Håvardstun and Holst 2013). In order to investigate this effect in detail, we have fabricated metal nanostructures on insulating borosilicate glass using electron beam lithography, a technique allowing us to tailor the design of our metal nanostructures and the area coverage. The measurements are intended to resembles normal working conditions and are therefore carried out using the commonly available secondary electron detectors found in conventional SEM's, namely an InLens detector and a Everhart-Thornley detector. We identify and discriminate several contributions to the shrinkage effect by varying microscope settings. We also present a method for estimating charge balance in insulating samples which can be used to estimate the measurement error. J. Goldstein et al., Scanning electron Microscopy and X-ray microanalysis Third Edition, Springer (2007) M. Greve, T. Håvardstun and B. Holst, Measuring the localized surface plasmon resonance effect on large arrays (5 mm × 5 mm) of gold and aluminum nanoparticles on borosilicate glass substrates, fabricated by electron beam lithography, Journal of Vacuum Science and Technology B, 31, 06F410 (2013) N. Okai, T. Yano and Y. Sohda, Charge Modeling for Metal Layer on Insulating Substrate, Japanese Journal of Applied Physics, 50, 06GC01 (2011) [ABSTRACT FROM AUTHOR]