Measurement of low energy secondary electron distributions using a double-pass cylindrical mirror analyzer

Abstract

A commercial double-pass cylindrical mirror analyzer (CMA) and standard Auger electron spectroscopy electronics have been adapted to measure the low energy portion (< 100 eV) of the secondary electron distribution. Under normal operating conditions for the CMA, the presence of stray electric and magnetic fields within the CMA plus the poor electron multiplier response at low energy prevent measurements in the region where the secondary electron distribution reaches its maximum (< 5 eV). To circumvent this problem, we apply an accelerating potential (70 V) to the “retarding” grid at the entrance of the CMA. The accelerating potential translates the secondary electron distribution to high enough energies that the theoretical response of the CMA ( E·N ( E)) is valid, but low enough to give reasonable resolution. Moreover, we are able to separate the small tertiary electron peak due to the outer (grounded) grid by applying a small accelerating potential to the sample. This use of the CMA for measuring secondary electron distributions allows the surface to be characterized by AES before and after measurement. We present results for clean copper and silver. In the log N( E) versus log E format, we observe the linearized cascade with Auger peaks clearly visible.