We report the realization of a novel superlattice which contains a high mobility (&bartil; 1.1×105cm2/V s at 4 K)degenerateelectron system. The structure consists of a wide, undoped AlxGa1−xAs well bounded by undoped (spacer) and doped layers of AlyGa1−yAs (y≳x) on both sides. The alloy composition in the well (x) is graded in such a way as to result in a parabolic potential with an additional sinusoidal modulation superimposed on it. Once transferred into this well, the electrons screen the parabolic potential and an electron system with a modulated charge density is obtained. We present self‐consistent quantum mechanical calculations of the electronic system, and report our characterization of the structure by secondary‐ion mass spectrometry and magnetotransport measurements.