Calculation of Electron Inelastic Mean Free Paths (IMFPs) VII. Reliability of the TPP-2M IMFP Predictive Equation

Published

March 1, 2003

Author(s)

S Tanuma, Cedric J. Powell, David R. Penn

Abstract

We report comparisons of electron inelastic mean free paths (IMFPs) determined from our predictive IMFP equation TPP-2M and reference IMFPs calculated from optical data. These comparisons were made for values of the parameter N^Ņ^ (the number of valence electrons per atom or molecule) that we have recommended and those that were recommended in a recent paper by Seah et al. (Surf. Interface Anal. 2001; 31: 778). The comparisons were made for eight elemental solids (K, Y, Gd, Tb, Dy, Hf, Ta, and Bi) and two compounds (KBr and Y₂O₃) for which there were appreciable differences in the recommended N_Ņ values from the two sources and for which optical data were available for the IMFP calculations. The average of the root-mean-square (RMS) deviations for the ten materials between IMFPs from the TPP-2M equation with our N_Ņ values and the reference IMFPs was 11.0 % whereas the corresponding average with the Seah et al. N_{Ņ values was 20.2 %. The larger average in the latter comparison was mainly due to large (> 20 %) RMS deviations for four materials (K, Hf, Ta, and KBr). For the other six materials, the RMS deviations with the Seah et al. values of} dν^ were similar to those with our values of N_{Ņ. Based on the comparisons for these ten materials, we believe it is preferable to use our values of N}dŅ in the TPP-2M equation.

Citation

Surface and Interface Analysis

Volume

35

Issue

No. 3

Pub Type

Journals

Keywords

auger electron spectroscopy, bismuth, dysprosium, electron inelastic mean free path, gadolinium, hafnium, potassium, potassium bromide, surface analysis

Citation

Tanuma, S. , Powell, C. and Penn, D. (2003), Calculation of Electron Inelastic Mean Free Paths (IMFPs) VII. Reliability of the TPP-2M IMFP Predictive Equation, Surface and Interface Analysis (Accessed December 15, 2024)