OBSERVATION OF THE DX CENTER IN PB-DOPED GAAS

Pb in GaAs introduces a DX center-like (metastable) defect level that is (229 +/- 16) meV above the GAMMA-conduction-band edge, in a similar energetic position to the Si and Sn related DX centers in GaAs. The p ersistent photoconductivity effect quenches at approximately 50 K, ind icating that the barrier to capture for the Pb and Sn dopants are simi lar. Despite the quite different atomic parameters of the Pb atom comp ared with the Sn atom, no significant chemical shifts have been found.