DX− center formation in planar-doped GaAs:Si in strong electric fields

Abstract

The kinetics of current decay and partial restoration in planar doped GaAs:Si due to the formation of DX− centers in strong electric fields has been experimentally studied. The existence of thresholds with respect to the field strength and donor concentration is explained. A model of the DX− center formation is proposed, which is based on the notions about variation of the depth and width of a potential well created by planar doping, caused by the redistribution of hot electrons between quantum confinement subbands. As a result, the energy level of DX− centers, which is situated above the potential well depth in the absence of strong field, decreases and falls within the potential well. This makes possible the DX− center formation, provided that hot electrons, occupying the resonance electron levels in the conduction band, simultaneously excite local vibrational modes.