Hot-electron capture to DX centers in Al_xGa_1-xAs at low Al mole fractions (x<0.2)

We report quantitative studies of hot-electron trapping by DX centers in short channel GaAs/n-AlxGa1-x As field-effect transistors. A remarkable result is that persistent hot-electron capture occurs even at very low values of the Al mole fraction, x≲0.2, where thermal capture is not observed. Thermal emission studies confirm that the trap state is associated with the DX center. Thus, for x≲0.2 the trap state is metastable, but can be persistently populated by heating the free electrons with an electric field. This and other features of the capture process support a large lattice relaxation model of the center.