A CALIBRATION OF THE H-C-AS STRETCH MODE IN GAAS

GaAs samples grown by chemical beam epitaxy and doped using (CBr4)-C-1 2 or (CBr4)-C-13 to give carbon concentrations of similar to 1 x 10(19 ) cm(-3) have been analysed by local vibrational mode infrared spectro scopy, secondary-ion mass spectrometry, Hall measurements and electroc hemical capacitance-voltage profiling. By exposure to a hydrogen plasm a similar to 80% passivation of the carbon was achieved. A calibration for the stretch mode of H-C-As pairs in GaAs has been established ind icating that an integrated absorption of 1 cm(-2) in the LVM line at 2 635.2 cm(-1) (H-C-12(As)) corresponds to a concentration of 9+/-2 x 10 (15) pairs/cm(3). This calibration is approximately half that of the m ost recently published value. Reasons for the difference are discussed .