Ballistic and dissipative electron transport in semiconductor superlattices

Ballistic electron transport is used to study the transmittance of GaAs/GaAlAs superlattices, In a three terminal device an energy tunable electron beam is injected via a tunneling barrier into an undoped superlattice and the transmitted current is measured as a function of the injector energy. Significant increase of the collector current is observed due to miniband conduction in the GaAs/AlGaAs superlattice. At flat band condition the transfer ratio alpha = I-C/I-E can be used to probe miniband position and miniband widths. Measuring the transfer ratio of superlattices at various bias conditions, a significant decrease of the miniband transmission with increasing electric field is observed, which can be attributed to the transition between coherent and incoherent transport in these superlattices. The results agree very well with theory. (C) 1998 Elsevier Science B.V. All rights reserved.