Charge Trapping by Deep Donors in Si-Doped AlxGa1-xAS

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Abstract
The kinetics of charge capture by deep donors in AlxGa1-xAs have been measured. The time dependence indicates that a single energy cannot be used to describe the trap. A model assuming thermally activated capture into a resonance in the conduction band with a range of energies gives excellent fits to the data and provides a measure of the energy range for the trap. This model is consistent with the large lattice relaxation model for DX centers. The increase of the activation energy for capture as the Al mole fraction is decreased contradicts the model which attributes the decay of the persistent photoconductivity to tunneling through the heterojunction barrier in modulationdoped structures.