PARAMAGNETIC CHARGE-STATE OF SUBSTITUTIONAL OXYGEN IN GAAS

In oxygen-rich GaAs the optical absorption of substitutional oxygen (O -As) in the near infrared was investigated by measuring its magnetic c ircular dichroism (MCDA). An MCDA was discovered which originates from a paramagnetic ground state. By investigating its thermal decay kinet ics and its dependence on optically induced recharging processes invol ving EL2 defects and by comparison with analogous local vibrational mo de measurements, it could be shown that the MCDA is due to the metasta ble B' charge state of the O-As centers. The B' state is thus identifi ed as the paramagnetic charge state of the O-As center. (C) 1995 Amen' cnn institute of Physics.