Continuum Wannier-Stark ladders strongly coupled by Zener resonances in semiconductor superlattices

We report the first experiment which relates electronic transport and intra band optical absorption in a biased superlattice. Wannier-Stark ladders far in the continuum and strongly coupled by Zener resonances are observed in an n-type GaAs/AlGaAs superlattice using infrared spectroscopy. Additional transport measurements reveal the formation of electric-field domains, with electrons tunneling resonantly to the next-nearest superlattice period.