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

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 n(2D). At low densities (n(2D) similar to 1.3 x 10(11) cm(-2)), the effective mass m{*} of the 2D electrons is 0.14 m(e), where m(e) is the free-electron mass. This value of 0.14 m(e) is twice the effective mass of electrons in GaAs (0.067 m(e)). m{*} increases with n(2D) and is similar to 0.16 m(e) at 2.7 x 10(11) cm(-2). We explain these results based on the formation of energy minibands along the superlattice direction. The electron scattering time tau is calculated from the mobility and effective mass data. At 0.3 K, tau increases with n(2D) from 5 to 11 ps as n(2D) is varied from 1.1 x 10(11) to 2.7 x 10(11) cm(-2). (C) 2000 American Institute of Physics. {[}S0003-6951(00)03323-4].