Investigation of DX centers in AlxGa1-xAs by space charge spectroscopy.

We present a critical analysis of both deep level transient spectroscopy and transient microwave absorption spectroscopy (MAS) for the case of DX centers in AlGaAs. We show that, even for a single level, a strongly nonexponential time dependence of the transients occurs. Our MAS experiments on Si-DX centers in Al0.3Ga0.7As extend the available data for the emission rates by more than three orders of magnitude. They are successfully interpreted by a single emission time constant using our model whereas at least three decay time constants are needed to explain the data by a pure exponential. Observed recapture processes in the neutral region of the sample underline the complexity of space charge spectroscopy in the case of the DX center.