ASSOCIATION OF A ZERO-BIAS ANOMALY IN ELECTRON-TUNNELING IN ALXGA1-XAS WITH THE DX DEFECT

A conductivity peak has been found at zero bias in electron-tunneling measurements on single-barrier GaAs/AlxGa1-xAs/GaAs junctions at 4 K i n the dark. The spectral dependence of the quenching of the peak has b een measured to extract a photoioization cross section which indicates that the peak is associated with the DX defect. Since zero-bias condu ctance peaks are a signature of tunneling via paramagnetic defects, th e data presented here are consistent with the existence of paramagneti c DX defects.