Effective mass enhancement of two-dimensional electrons in a one-dimensional superlattice potential

Abstract

We report effective mass enhancement of two-dimensional (2D) electrons in an atomically precise one-dimensional AlGaAs/GaAs superlattice potential fabricated by the cleaved-edge overgrowth technique. Magnetotransport measurements reveal that the mobility of the 2D electrons increases with electron density n2D. At low densities (n2D∼1.3×1011 cm−2), the effective mass m* of the 2D electrons is 0.14 me, where me is the free-electron mass. This value of 0.14 me is twice the effective mass of electrons in GaAs (0.067 me). m* increases with n2D and is ∼0.16 me at 2.7×1011 cm−2. We explain these results based on the formation of energy minibands along the superlattice direction. The electron scattering time τ is calculated from the mobility and effective mass data. At 0.3 K, τ increases with n2D from 5 to 11 ps as n2D is varied from 1.1×1011 to 2.7×1011 cm−2.