Determination of carbon,silicon and boron content in semi-insulating GaAs by infrared absorption spectroscopy

Measurements of the local vibrational mode (LVM) absorption of ¹²C_As at 582 cm⁻¹, ²⁸Si_Ga at 384 cm⁻¹ and ⁽¹⁰⁾¹¹B_Ga at (540 cm⁻¹) 517 cm⁻¹ can be used to determine the concentration of these residual impurities in semi-insulating (SI) GaAs. Although the energy-limited resolution of a grating spectrometer does not allow measuring the line shape of the narrow LVM bands in GaAs the intensity of it determined with definite spectral slit width (SSW) is a reliable measure for the respective impurity content. Calibration factors given in the literature and peculiarities in the measurements and evaluations for the different impurities are discussed.