Signature of the gallium-oxygen-gallium defect in GaAs by deep level transient spectroscopy measurements

Experimental results of deep level transient spectroscopy (DLTS) and Fourier transform infrared spectroscopy (FTIR) on oxygen-doped GaAs crystals are presented. A positive identification of the DLTS signature of the Ga-O-Ga defect (tentatively identified as an oxygen-arsenic vacancy complex) is made through correlation with FTIR measurements. The energy level for the two-electron state of the defect is found to be located at 0.55 eV below the conduction band, and direct proof is given that this center is actually a negative U center. A calibration factor for local vibrational mode absorption is calculated to be 8×1016 cm−1.