Alternating donorlike-acceptorlike configurationally bistable defect in irradiated phosphorus-doped silicon

Using deep-level transient spectroscopy we have detected a new configurationally bistable defect in heavily phosphorus-doped silicon, electron irradiated at room temperature. The center has the unique property of being electron attractive in one of its configurations and hole attractive in the other. The activation energies for electron and hole emission for the corresponding traps are determined as 0.42 and 0.15 eV, respectively. The configurational transformation of this center can be activated by the cool-down of the sample under applied zero, forward, or reverse bias, but also by certain electrical pulsing schemes. A general model for the bistable defect as a close deep donor-acceptor pair is suggested, where the configurational transformation is accompanied by a partial internal charge transfer in the neutral charge state of the complex defect.