In addition to the persistent photoconductivity (PPC) attributed toDXcenters in GaAs delta-doped with Si, a weak PPC (WPPC) with a PPC carrier density independent of Si-doping concentration has been generally reported at ambient atmosphere, but the nature of the deep states responsible has not been elucidated. Here, we present the results of a detailed study of the WPPC in &dgr;-GaAs:Si at low-doping densities,NSi≈1–3×1012&hthinsp;cm−2,and ambient pressure. It is concluded that the WPPC does not arise fromDXcenters but from another deep defect, which isDX-like in the sense that it can be metastably excited. The presence of two distinctDX-like states is apparent from two separate annealing temperatures of the PPC,Ta≈50 KandTb≈230 K;to the best of our knowledge, the latter is the highest annealing temperature observed in the AlGaAs:Si system. ©1998 American Institute of Physics.