Impurity state electroabsorption studies in oxygen-doped GaAs

Electroabsorption measurements at 300 K made within the band gap on high resistivity GaAs:O are reported. For a crystal with the Fermi level at 0.54 eV, major structure has been detected at 0.52, 0.57, 0.67, 0.75, 0.87, 0.93, 1.03, 1.12, 1.25, 1.36, and 1.39 eV. The 0.67 eV peak appears only in the second harmonic spectrum, indicating no change in permanent dipole for this transition. Polarized light, lock-in amplifier phase angle, and applied field variation data are presented.