Trace element accelerator mass spectrometry

Trace impurities including B, N, F, Mg, P, Cl, Cr, Fe, Ni, Co, Cu, Zn, Ge, As, Se, Mo, Sn and Sb in semiconductor materials (Si, SiGe, CoSi2, GaAs and GaN) can also be measured by TEAMS (trace element accelerator mass spectrometry), which utilizes a secondary ion source in an accelerator mass spectrometer.51 TEAMS is an interesting complementary technique to SIMS and can eliminate interferences that may not be resolvable in SIMS. 

Trace element accelerator mass spectrometry (TEAMS) can also be applied for depth profiling as demonstrated for H, , , A1 and Si implants (and impurities) in semiconductor GaN substrate.115... 

FIGURE 40.21 Comparison of the depth profiles of a copper impurity by trace element accelerator mass spectrometry (TEAMS) and secondary ion mass spectrometry (SIMS). Reprinted from McDaniel, ED, Datar, S.A., Nigam, M., Ravi Prasad, G.V. (2002) Impurity measurements in semiconductor materials using trace element accelerator mass spectrometry. Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms, 190 1-A), 826-830. Copyright (2002), with permission from Elsevier Science. 

McDaniel, F.D. (2003) Trace element accelerator mass spectrometry. In Characterization of Materials, edited by Kaufmann E.N., Hoboken, NJ Wiley-Interscience, pp. 1235-1258. 

McDaniel, F.D., Datar, S.A., Guo, B.N., Renfrow, S.N., Zhao, Z.Y, Anthony, XM. (1998) Low-level copper concentration measurements in sUicon wafers using trace-element accelerator mass spectrometry. Applied Physics Letters, 72,3008-3010. 

This book is not intended to cover important branches of mass spectrometry that provide accurate and precise quantitative measurements of relative concentrations, e.g., of variations in isotopic ratios of an element by isotope ratio mass spectrometry (IRMS) and accelerator mass spectrometry (AMS). Rather, this book is mainly concerned with determinations of absolute amount of substance (see Chapter 1 for a definition and explanation), particularly for compounds present at trace levels in complex matrices. (The only exception is the inclusion of a brief description of methods used to determine differences in levels of proteins in living cells or organisms subjected to different stimuli, e.g., disease state vs normal state). 

In VoL 2 of this handbook, the origin of elements has been discussed in detail. Therefore, the present authors will exclude that part, except for some comments on the importance of particular radionucKdes. In this chapter, the principles and instrumentation of accelerator mass spectrometry (AMS), the key player for detection of cosmological radionucKdes in ultra trace scale, will be discussed in detail. Detailed discussion of all the research works carried out to date with cosmogenic radionuclides is out of scope. Only the detection of million-year half-life radionucKdes in ultra trace concentration will be touched, followed by concise description of the required chemistry. Rather than giving a general description, a few of them have been chosen and described in separate sections. Inductively coupled plasma-mass spectrometry (ICP-MS), thermal ionization mass spectrometry (TIMS), secondary ion mass spectrometry (SIMS), or resonant laser ionization mass spectrometer (RIMS), etc. have also been used for detection of cosmogenic radionucKdes. However, these techniques have much lower sensitivity compared to AMS. Brief discussions on these instruments have been appended at the end of this chapter. This chapter ends with a conclusion. 

Lu Z-T, Wendt KDA (2003) Rev Sci Instrum 74 1169 Maiti M, Lahiri S (2008) Accelerator mass spectrometry-an ultrasensitive probe for elemental analysis. In Lahiri S (ed) Trace analysis. Narosa Publishing House, New Delhi, pp 145-171 Maji S, Lahiri S, Wierczinski B, Korschinek G (2006a) Anal Chem 78 2302... 

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