Although there are many advantages in SEM measurement methods at ultra-low and low accelerating voltages, it is very important to select a proper accelerating voltage in a wide range from ultra-low accelerating voltage to high one (30kV) according to the purpose of observation of samples.
Studies on imaging of CNTs/polymers have been made within 0.3~5kV of accelerating voltages by FE-SEM with an in-lens detector, but few studies on observation of the surface microstructure of CNTs were conducted by SEM equipped with standard second electron detectors.
Pak Il Man, a section head at the General Assay Office, has performed a theoretical analysis on observation of the microstructure of CNT surface and observed the image of microstructure of CNT surface by Quanta 200 SEM, thus proposing a new method for selecting a proper accelerating voltage.
First, considering the theoretical resolution of Quanta 200 SEM and the size of electron-CNTs interaction range according to acceleration voltage, he made a theoretical study on selection of a proper accelerating voltage.
Second, he performed an observation of SEM images of CNTs at various accelerating voltages.
The effects of energy of the incident electron on the size of the electron-CNTs interaction range and the resolution of SEM were theoretically investigated. As a result, in the case of microstructure observation of CNTs surface by SEM, the most proper accelerating voltage was in the range of 5~10kV.
Through the experiments based on it, he found that the accelerating voltage of 7.5kV enables us to get the sharpest image of the microstructure of CNT surface.
More information is available in his paper “Optimization of the Accelerating Voltage in the Fine Structure Observation of Carbon Nanotube Surface by SEM” in “International Journol of Research and Scientific Innovation” (EI).
© 2021 KumChaek University of Technology