Mobility modulation on a modulation-doped structure with an AlAs/GaAs fractional layer superlattice

Abstract

The mobility modulation effect of AlAs/GaAs fractional layer superlattices in an AlGaAs/GaAs modulation-doped structure, which is used for quantum wire and electron wave interference transistors, is investigated by measuring their sheet electron concentration (ns). The ns obtained by the Shubnikov–de Haas oscillation is the number of high-mobility electrons. On the other hand, the ns calculated from structural parameters is the total number of the high- and low-mobility electrons. The relationship between the electron mobility and ns is found to be μ∝(ns − nc)γ, where γ=1 and nc=5.9×1011 cm−2. The mobility modulation part in the transconductance exceeds the electron concentration modulation part by a factor of 3.