Relocation dynamics of domain boundaries in semiconductor superlattices

Abstract

The formation of static electric-field domains in doped semiconductor superlattices appears in the current-voltage $(I\ensuremath{-}V)$ characteristics as multiple current branches separated by abrupt discontinuities. The switching dynamics of the charge-accumulation layer forming the domain boundary is experimentally investigated at dc voltages in the first plateau of the $I\ensuremath{-}V$ characteristic for different polarities and amplitudes of the applied voltage steps. When the voltage is decreased (down jumps) from its initial dc value, the accumulation layer can directly move from its initial position to its final position, in accordance with the direction of the applied voltage step. However, when the voltage is increased (up jumps), there are two different modes of the relocation motion of the accumulation layer. For small up jumps, the accumulation layer can still move directly from its initial to its final position. When the amplitude of the transient current peak is above a critical value, a charge dipole is injected at the emitter contact, in addition to the existing monopole formed by the domain boundary. The experimentally observed switching behavior is in excellent qualitative agreement with recent theoretical work [A. Amann et al., Phys. Rev. E 63, 066207 (2001)].