D X-center-like traps and persistent photoconductivity in Te-doped AlxGa1−xSb on GaSb

The donor-related deep electron traps in Te-doped Alx Ga1−x Sb on GaSb substrate were investigated by deep level transient spectroscopy, capacitance-voltage, photocapacitance, and Hall-effect measurements. Deep electron traps were not detected in the Al composition range 0≤x<0.2, but were detected in the higher range of x. The concentration of the deep electron traps increases steeply with x and then saturates. The concentration also increases linearly with donor concentration for the same Al composition. In the temperature-dependent Hall-effect measurement, both shallow donor and deep donor levels were observed. The deep donor is dominant for x≥0.4, and the thermal activation energy E0 increases dramatically from 6 to 110 meV in the range of 0.2<x≤0.5. Persistent photoconductivity was observed for x≥0.3 at temperatures below 100 K. All the experimental results indicate that the deep electron traps in Te-doped Alx Ga1−x Sb are quite similar to the DX center in Alx Ga1−x As.