The first observation of scattering-controlled transmission resonances in superlattices is reported. These originate from states supported by subsets of the superlattice of thickness equal to the electron coherence length. At lower electric fields a broad region of negative differential conductance due to progressive field-induced wave-function localization is also observed. This phenomenon is shown to be physically equivalent to the Bragg-diffraction-induced negative differential conductance predicted by Esaki and Tsu in 1970.

• Received 27 February 1990

DOI:https://doi.org/10.1103/PhysRevLett.64.3167