Evidence for the negative charge state of DX centres in AlxGa1-xAs:Si

Abstract

The authors study the thermally activated capture of electrons on Si-induced impurity states (DX centres) in AlxGa1-xAs (x=0.28 and 0.33) after photoionization at low temperature (65-160 K) and under pressure (0-8 kbar). They show that the combination of isothermal and thermostimulated experiments under pressure permits one to state that the capture rates onto the different configurations of the DX centre related to the local environment of the donor atom in the AlxGa1-xAs alloy are not very different from each other, and to unambiguously discriminate between the cases DX0 and DX-. The results indicate a negatively charged DX ground state.