Detection Limits for some Elements in silicon SIMS can do trace element analysis WDS-100ppm Primary lon Beam O, or Cs EDS 1000ppm Element Detection limit Element Detected Ion atom/cm3 B 0.002 <1014 BPAScoNH 31P/31P+ 0.1 <5×1015 75AS- 0.2 <1016 121Sb 1.0 5×1016 C 1.0 5×1016 16O 10 5×10 5×10 H 100 5×1018 Detection limit Count rate limited is affected by Instrument transmission or ionization efficiency INstrumental backgrounds Residual vacuum or components of the instrument lon interferences matrix, primary beam and instrumental speciesSIMS can do trace element analysis Detection limit is affected by WDS ~100ppm EDS ~1000ppm