Detection of traces in semiconductor materials by two-color laser-enhanced ionization spectroscopy in flames

In this paper we demonstrate that two-color laser-enhanced ionization (LEI) spectroscopy in flamescan be used for detecting impurities at a sub-ppm level in GaAs. Six elements were investigated(Co, Cr, Fe, In, Mn, Ni), and the content could be determined for three of them (Cr, Fe, Ni), while only an upperlimit below ppm could be given for the other three. The analysis was performed on the bulk material whichwas dissolved in acid and further diluted. In the diluted solution, the detection limits were of the same orderas in pure water solutions. Spectral interferences have been corrected for by using a background correctionmethod, which is performed without scanning the lasers. Furthermore, we discuss the applicability of LEI inflame and graphite furnace to samples with various impurity elements, matrices, and total amounts of sampleavailable for analysis.