Development of a reference material and reference method to provide a calibration of the instrument intensity scale for differential AES

Abstract

The irreproducibility of Auger electron spectra recorded in different laboratories arises through uncalibrated instrument functions. For spectra recorded in the direct mode a calibration method and reference materials have been developed which give the calibration for an instrument to convert spectra over the energy range 10–2500 eV to true spectra with a standard deviation of 3%. A reference material of solid copper and gold is developed here with reference data and a reference method to provide a similar calibration for Auger electron spectra recorded in the differential mode using a 5 keV electron beam incident at 30° to the surface normal. The calibration involves the use of both 5 and 10 eV sinusoidal analogue modulations and provides 9 calibration points between 60 and 2100 eV on the energy scale. Tests using both cylindrical mirror analyser and spherical sector instruments show that a calibration accuracy of ±5% may be achieved so that all instruments analysing the same material under the same beam energy, angle of incidence, spectrometer resolution and modulation should give the same spectra within that limit.