Determination of the occupancy level of the DX center resonant with the conduction band in Te-doped algasb

e analysis of the amplitude of the deep level transient spectroscopy signal due to DX centers is exploited to determine the E-DX occupancy level of the DX center in Te-doped AlxGa1-xSb in the range of low values of x where E-DX is resonant with the conduction band. We take advantage of a small but still detectable change in the occupancy factor of the DX level induced by the filling pulse. It is shown that E-DX is very close to the L conduction band edge for xless than or equal to0.20. This behavior is different from the one at xgreater than or equal to0.30 where E-DX lies in the forbidden energy gap and exhibits an x dependence similar to the X edge. These results are discussed at the light of different atomic configuration for DX centers at an anion-substitutional impurity.