Spectroscopic study of intraminiband and interminiband tunneling in finite superlattices

We present a tunneling density-of-states study of transport between minibands in a series of Gaₓ{Al}_{1{{-}}x}$As superlattice structures. We observe the eigenstates of the finite superlattice systems below the Stark localization threshold by tunneling spectroscopy. The tunneling spectroscopy agrees well with self-consistent Thomas-Fermi calculations. The eigenstate strengths are observed to thermally broaden as expected, and evidence for longitudinal-optical-phonon replicas of the eigenstate structure is presented.