Field-induced real-space transfer in δ-doped GaAs

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Abstract
The differential conductivity in various systems of parallel δ layers in GaAs as a function of electric field shows a maximum with subsequent saturation at about 10 V/cm, which manifests itself also in the weak-field magnetoresistivity and Hall effect. The temperature behavior of the peculiarities in the differential conductivity has been studied and compared with results obtained from a balance equation approach to a square-well superlattice taking strict dynamical screening into account. Three effects due to carrier heating in the electric field turn out to be important. A real-space transfer of electrons into the region between the layers and the increase in the electron drift velocity lead to a strong rise of the differential conductivity at lower fields. When heating becomes more and more balanced by the emission of optical phonons the differential conductivity goes through a maximum and saturates.