Trace and ultratrace analysis of gallium arsenide by different mass spectrometric techniques

The capability of different solid-state mass spectrometric methods [spark source mass spectrometry (SSMS), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), radiofrequency glow discharge mass spectrometry (rf GDMS) and secondary ion mass spectrometry (SIMS)] in comparison with inductively coupled plasma mass spectrometry (ICP-MS) was investigated by the trace analysis of GaAs. For trace analysis using solid-state mass spectrometry, a semiconducting laboratory GaAs standard (using high-purity GaAs) doped with Zn, B, Si, Ge, Sn, Sb, P, S, Se and Te (in the mu g g(-1) concentration range) was prepared by the liquid encapsulation vertical Bridgeman technique. A selected piece of the synthetic laboratory GaAs standard was investigated directly by SIMS, SSMS, rf GDMS and LA-ICP-MS. For the quantification of SIMS measurements single element ion-implanted GaAs certified reference standards were used. After dissolution of the GaAs sample in high-purity HNO(3)-H(2)O(2), the concentrations of the doped elements mere measured by ICP-MS and inductively coupled plasma atomic emission spectrometry (ICP-AES). By using the results of SIMS, ICP-MS and ICP-AES for the selected piece of the synthetic laboratory GaAs standard, relative sensitivity coefficients (RSCs) of the elements in SSMS, rf GDMS and LA-ICP-MS were determined. The experimentally determined RSCs were used for correcting measured concentrations in an unknown GaAs sample. In order to reduce matrix effects in ICP-MS, a procedure for complete GaAs matrix separation in a chlorine-argon stream at 280 degrees C was evaluated. The recoveries of 24 elements after the chlorination of GaAs were determined to be nearly 100% (except for Sn and Ta), Ultratrace analysis of semiconducting GaAs after matrix separation was carried out by double-focusing sector field ICP-MS. The detection limits of ultratrace elements in GaAs after matrix separation (in the tom ng g(-1) concentration range) mere better by about one order of magnitude compared with measurements without matrix separation and were comparable to those obtained by solid-state mass spectrometry.