Identification of Background in CMA

Abstract

  We studied the background in electron spectroscopy that was caused by the scattering of signal electrons in the specific cylindrical mirror analyzer (CMA) developed for absolute Auger electron spectroscopy. For this, a mini-electron gun was set at a sample position to calibrate the trajectories of signal electrons in the CMA. The electron beam current (i_in) entering the CMA was measured using a retractable Faraday cup and the detected current (i_out) was measured using another Faraday cup (normally used for detecting Auger electrons). It was revealed that the two meshes spun in the inner cylindrical electrode act as micro lenses for signal electrons, significantly deteriorating the CMA characteristics by the deflection and scattering of the signal electrons in the CMA. The measured energy spectra demonstrated the excellent performance of electron spectrometry with a signal to noise ratio of ～10⁷.