Electron backscattering coefficient, material contrast and response function of BSE- detectors in scanning electron...

An empirical expression for the electron backscattering coefficient η, mean backscattered energy coefficient ε and response function F of backscattered electrons (BSE) detectors in scanning electron microscope (SEM) are established for bulk specimens in dependence of atomic number Z and primary electrons energy E_B. The obtained expressions give more precisely data of η than all previous publications in the wide energy range E_B 1-30 keV. They were used to describe the dependence of the BSE signal I_S from atomic number of the target material Z and SEM accelerating voltage E_B. The image contrast as a function of Z -differences and E_B is considered. Particular attention is paid to the influence of the response function F on the formation of the I_S signal. All consideration were carried out with commercial semiconductor or scintillation BSE - detectors installed in SEM in standard position below from objective lens and right above the sample. The characteristics were compared with similar of the multichannel plate (MCP) detector.