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An analytic form for the SIMS response function measured from ultra‐thin impurity layers
Author(s) -
Dowsett M. G.,
Rowlands G.,
Allen P. N.,
Barlow R. D.
Publication year - 1994
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740210508
Subject(s) - deconvolution , convolution (computer science) , silicon , dirac delta function , fourier transform , computational physics , function (biology) , error function , noise (video) , range (aeronautics) , chemistry , analytical chemistry (journal) , materials science , mathematical analysis , mathematics , physics , optics , algorithm , optoelectronics , composite material , chromatography , machine learning , evolutionary biology , artificial intelligence , computer science , artificial neural network , image (mathematics) , biology
We present an analytic form for the response function measured in a SIMS depth profile of an impurity layer less than 1 nm wide (a delta layer). Although the process used to evolve the function can be justified on physical grounds, we make no claim that the justification is rigorous or that the function is universal. At present we examine its use in making a consistent and utilitarian definition of frequently employed resolution parameters. The function is found to give an accurate fit (lying everywhere within the statistical noise on the profile over several orders of magnitude in signal intensity) to responses from boron, antimony, germanium and isotopically pure silicon deltas in a silicon matrix, and to silicon, aluminium and beryllium deltas in gallium arsenide. The fit is also good over the full primary ion energy range examined (1–11 keV). There are four fitting parameters for a normalized data set, one related to the depth of the delta below the surface and three independently related to depth resolution. The function has an analytic Fourier transform, and may be used as a smooth, noise‐free substitute for the measured data in profile synthesis (convolution) and in deconvolution whenever convolution is a valid model for the SIMS measurement process.