Selectively doped single period AlxGa1−xAs/GaAs heterojunctions with the GaAs layer on top of AlxGa1−xAs were prepared by molecular beam epitaxy. Moderate electron mobility enhancement was achieved when the samples were grown near a substrate surface temperature of 700 °C. Samples grown well below and well above 700 °C did not show observable mobility enhancement. The samples grown at 700 °C and with an electron concentration of 1017cm−3exhibited 300 K mobilities of about 4 500 cm2/Vs and 78 K mobilities of 8500 cm2/Vs, which is about a factor of 2 higher than that of bulk GaAs at 78 K. To our knowledge, this is the first report of mobility enhancement in these inverted single period AlxGa1−xAs/GaAs heterostructures.