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Quantitative profiling of SiGe/Si superlattices by time‐of‐flight secondary ion mass spectrometry: the advantages of the extended Full Spectrum protocol
Author(s) -
Py M.,
Barnes J. P.,
Lafond D.,
Hartmann J. M.
Publication year - 2011
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.4904
Subject(s) - chemistry , secondary ion mass spectrometry , mass spectrometry , analytical chemistry (journal) , dopant , impurity , doping , ion , superlattice , germanium , optoelectronics , silicon , materials science , chromatography , organic chemistry
The abundance of work on SiGe‐based devices demonstrates the importance of the compositional characterization of such materials. However, Secondary Ion Mass Spectrometry (SIMS) characterization of SiGe layers often suffers from matrix effects due to the non‐linear variation of ionization yields with Ge content. Several solutions have been proposed in order to overcome this problem, each having its own limitations such as a restricted germanium concentration range, or a weak sensitivity to dopants or impurities. Here, we studied the improvements brought by an alternative protocol: the extended Full Spectrum protocol, which states proportionality between the composition of the secondary ion beam and that of the actual material. Previous studies on this protocol showed that it was extremely precise and reproducible for Ge quantification in a permanent regime, because of minimized matrix effects. In this study we thus investigated its accuracy for the simultaneous quantitative depth profiling of both matrix elements (Si, Ge) and impurities (B, C or P) in strained SiGe/Si superlattices by comparing results with those from more classic protocols. The profiles provided by the extended Full Spectrum protocol were found to be accurate, and to exhibit better properties than classic protocols in terms of signal/noise ratio and signal stability, along with a slight enhancement in depth resolution. Copyright © 2011 John Wiley & Sons, Ltd.