Sequential Resonant Tunneling in Superlattices: Light Scattering by Intersubband Transitions

Abstract

The phenomenon of sequential resonant tunneling (SRT) refers to a transport mode of superlattices where the usual resonant tunneling is followed by carrier decay through the emission of phonons.1–9 When this form of transport is preferred, samples spontaneously break into electric-field domains characterized by the alignment of particular subbands in neighboring wells. This leads to considerable structure in the I-V (current-voltage) response associated with the motion of domain boundaries.1–9 Following the pioneering work of Esaki and Chang on GaAs-AlAs superlattices, there have been many studies of SRT involving transport “ and, more recently, photoluminescence techniques.6–9 The latter, in particular, allows one to directly probe the field in the domains and the domain pattern through measurements of Stark shifts. Moreover, the carrier density can be easily varied by means of photoexcitation. This provides an additional experimental knob that is useful for understanding domain formation.