Effect of indium on the properties of DX centers in Si-doped In _y(Ga_0.3Al_0.7)_1-yAs

The addition of In to Si-doped Al0.3Ga0.7As has been investigated to determine its effect on DX centers. As expected, the persistent photoconductivity of the material is reduced as the band gap decreases with increasing In concentration. In addition, a new deep level transient spectroscopy peak is observed for the first time, which we attribute to DX centers having near In neighbors. This is clear evidence that the DX levels are highly localized states associated with donor impurities, whose properties are very sensitive to the local atomic configuration near the donor atom. This work supports previously published work on the effects of alloy disorder on DX centers, which is the strongest evidence to date for the microscopic configuration of the DX level.