Native hole trap in bulk GaAs and its association with the double-charge state of the arsenic antisite defect

Abstract

We have identified a dominant hole trap in p-type bulk GaAs employing deep level transient and photocapacitance spectroscopies. The trap is present at a concentration up to about 4×1016 cm−3, and it has two charge states with energies 0.54±0.02 and 0.77±0.02 eV above the top of the valence band (at 77 K). From the upper level the trap can be photoexcited to a persistent metastable state just as the dominant midgap level, EL2. Impurity analysis and the photoionization characteristics rule out association of the trap with impurities Fe, Cu, or Mn. Taking into consideration theoretical results, it appears most likely that the two charge states of the trap are the single and double donor levels of the arsenic antisite AsGa defect.