A simple method of thin film analysis in the electron probe microanalyser

Abstract

A simple method is proposed for calculating by hand the thickness of surface films using data obtained from the microprobe analyser. It is shown that, if one exploits the scaling properties of electron scattering distributions, a set of curves may be obtained representing the fraction of characteristic ionization produced within a surface layer the thickness of which is expressed as a fraction of the Bethe range. From these curves the thickness of surface layers ranging from less than 1 μg cm⁻² up to several mg cm⁻² may be rapidly estimated from microprobe measurements. The precision of this approach is at present limited by errors in the electron scattering model used to produce the curves, which lead to a systematic underestimate of film thickness in the region of 15%. With improved scattering data this method should be capable of a precision of ±10% in most practical cases.