Infrared optical absorption and Hall-effect techniques were employed to study deep defects in As-rich molecular-beam-epitaxial GaAs layers grown at very low temperature (200°C). A large ir absorption band was observed between 0.55 eV and the band edge. This band is composed of photoquenchable and photounquenchable components. Photoquenching, thermal recovery from the metastable state, and ir absorption properties of the quenchable defect, of estimated concentration ~3x1018 cm-3, are identical to those of EL2. On the other hand, the unquenchable defect, of estimated concentration ~3x1019 cm-3, resembles the isolated AsGa, antisite observed in neutron-irradiated GaAs. Both defects' concentrations, which show different isothermal annealing behavior, are reduced by about an order of magnitude upon thermal annealing of 600°C for 10 min. This reduction is accompanied by an increase of sample resistivity by a few orders of magnitude.
Manasreh, M. O.,
Look, D. C.,
& Evans, K. R.
(1990). Infrared-Absorption of Deep Defects in Molecular-Beam-Epitaxial GaAs-Layers Grown at 200°C - Observation of an EL(2)-Like Defect. Physical Review B, 41 (14), 10272-10275.