Samples of Te-doped liquid-phase epitaxial layers of Ga1-xAlxAs were investigated by using magneto-optical and optically-detected electron paramagnetic resonance methods. After illumination at low temperatures, a paramagnetic defect was detected in samples (Ga0.52Al0.46As) with an indirect band gap. It was associated with the metastable photo-ionized state of the DX-center, because of its correlation with persistent photoconductivity. The spectral shape and onset energy of the magnetic circular dichroism of absorption were comparable with those that had previously been detected by means of infra-red absorption measurements. In the case of magnetic circular dichroism of absorption-detected electron paramagnetic resonance, a single isotropic line was found which exhibited no hyperfine splitting. The paramagnetic state was attributed to an EMT-like state and the magnetic circular dichroism of absorption was explained in terms of a photo-ionization transition from this electron paramagnetic resonance state to a higher conduction band minimum which was derived from the X band.

M.V.B.Pinheiro, M.Linde, H.Ohkura, J.M.Spaeth: Materials Science Forum, 1995, 196-201, 1085-90