Coexistence of the DX center and other Si-related electron bound states in Al1-xGaxAs

The coexistence of the DX center with other donor-related bound states has been investigated in Si-doped direct gap AlxGai-xAs, by comparing electron denisty data obtained by capacitance/voltage and Hall measurements. The experiments were carried out under saturated persistent photoconductivity conditions, as well as during isothermal capture transients. A D degrees bound state degenerated in energy with the conduction band is populated through low temperature photo-ionization of the DX center. The D degrees level comes very close in energy to the Gamma minimum when the direct-to-indirect gap transition is approached. Under defined conditions, the final stage of isothermal capture transients is dominated by the electron freezing into hydrogenic bound states linked to Gamma.