Optimum parameters for combined Auger‐ionization loss coincidence spectroscopy in the reflection mode

The detection limit of AES can be improved by combined Auger‐electron loss coincidence spectroscopy (AES‐ILSCS) as proposed by Cazaux. Using an arrangement with two hemispherical analysers and large‐angle collectors, experimental parameters are optimized by (1) matching the energy windows Δ E s of the spectrometers to achieve a large peak/background ratio, (2) setting the angular positions to obtain identical sampling depths for AES and ILS and (3) tilting the sample and using an adjustable electron gun at glancing incidence to get a large ILS signal. False coincidence can be reduced by small Δ E s and using very fast detectors in the coincidence mode for post‐accelerated AES and ILS electrons. Based on Langeron's data, the estimated coincidence signal/false coincidence noise ratio is ∼1 for 10 −4 Fe coverage on an Si substrate using 9 keV, 10 nA primary electrons and a Δ t ≈︁1 ns coincidence interval. The detection limit can be improved by a factor of 10 2 with respect to conventional AES.