High sensitivity measurement of implanted As in the presence of Ge in GexSi1-x/Si layered alloys using trace element accelerator mass spectrometry

Various devices can be realized on strained GeSi/Si substrates by doping the substrate with different impurities such as As. As is an n-type dopant in both Ge and Si. As cross contamination can also arise during germanium preamorphization implantation due to inadequate mass resolution in the implanter. Thus, it is important to be able to accurately measure low-level As concentrations in the presence of Ge. Secondary ion mass spectrometry (SIMS) is the standard technique for these types of measurements but is constrained by mass interferences from molecular ions ((74)GeH, (29)Si(30)Si(16)O). The trace element accelerator mass accelerator technique allows the breakup of interfering molecules. As is measured in a GeSi matrix with sensitivity significantly better than SIMS. (C) 2000 American Institute of Physics. [S0003-6951(00)02450-5].