Miniband formation at finite electric fields in a graded-gap superlattice


We have investigated a graded-gap superlattice with differential photocurrent spectroscopy at 77 K. The lowest conduction subband exhibits with increasing electric field a transition from localized to extended miniband states and back to localized states. The transition from the extended miniband states at finite electric fields back to localized states is observed. Calculations of the miniband width using different methods support the interpretation of miniband formation at finite electric fields.

Europhys. Lett. 23, 283 (1993)