Analysis of electrically active carbon in semi-insulating gallium arsenide by infrared absorption spectroscopy

Cal bon in semi-insulating gallium arsenide (GaAs) crystals has been investigated by Fourier-transform IR absorption spectroscopy, spark source mass spectrometry, and charged particle activation analysis. Procedures for the quantitative evaluation of the 582-cm(-1) local mode absorption due to carbon on the arsenic sublattice (C-As) are described. The strength of the mode shows a linear correlation with total cal bon content measured by spark source mass spectrometry over the concentration range from 3 x 10(14) to 2 x 10(16) cm(-3). The new calibration factor for the integrated absorption at 77 K is (7.2 +/- 0.4) x 10(15) cm(-1), based on a relative sensitivity coefficient of 3.2 +/- 0.1 of the spark source mass spectrometry. Calibration factors for the IR absorption method at room temperature are also given.