Hole-capture cross section ofDXcenters inGa1−xAlxAs

We have measured the cross sections associated with electron and hole capture on the DX center in liquid-phase-epitaxially grown, Te-doped ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Al}}_{\mathit{x}}$As for various alloy compositions x. The results obtained demonstrate that the DX center in direct-band-gap material (i.e., up to x=0.4) is not responsible for the minority-carrier lifetime, which has been measured independently. The barriers associated with electron and hole captures have been determined from the variations of the corresponding cross sections versus temperature in the x=0.4 material. These barriers are not compatible with a capture process via multiphonon emission, which suggests that this defect is not associated with a large electron-phonon interaction.