Temperature dependence of local vibrational mode optical absorption for carbon acceptors in GaAs

The local vibrational mode (LVM) absorption band due to CAs in GaAs is reported for three semi-insulating samples at room temperature and for T<77 K. Data obtained by Fourier transform infrared spectroscopy at resolution values from 1.0 to 0.1 cm−1 indicate that the area of the carbon LVM band increases by ∼60% upon cooling from room temperature, a substantially larger increase than some accounts have suggested. Our recommended value for the calibration factor f in going from LVM band area to carbon concentration is fRT≂1.6fLT ≂(13±3)×1015 cm−1.