High-field transport in superlattices: observation of the Stark-cyclotron resonance

Electron transport in heterojunction superlattices under intense electric and magnetic fields is investigated. In the case of parallel fields, current resonances are shown for particular ratios of electric and magnetic fields satisfying the Stark-cyclotron resonance (SCR) condition. At SCR the potential drop per period is an integer multiple of the magnetic quantization energy and elastic tunneling transport between Landau levels belonging to neighboring wells becomes possible. Unambiguous demonstration of SCR in an appropriately tailored GaAs/AlGaAs superlattice is given for transitions involving up to four Landau-level index change. In the case of orthogonal electric and magnetic fields, a substantial suppression of the miniband current is reported. This is due to the magnetic-field induced localization of superlattice electronic states. (C) 1997 Academic Press Limited.