Observation of Esaki-Tsu negative differential velocity in GaAs/AlAs superlattices

Abstract

The perpendicular peak velocity and critical field have been measured in a series of GaAs/AlAs superlattices as a function of the miniband width and miniband position relative to the AlAs X confined levels. The data cannot be explained by the electric-field localization mechanism [R. Tsu and G. D\"ohler, Phys. Rev. B 12, 680 (1975)] in the range of superlattice parameters investigated, but is qualitatively understood in terms of electron acceleration within the miniband [L. Esaki and R. Tsu, IBM J. Res. Develop. 14, 61 (1970)].