High-mobility variable-density two-dimensional electron gas in inverted GaAs-AlGaAs heterojunctions

Inverted heterointerfaces (GaAs on AlGaAs), which are basic constituents of all quantum wells and superlattices, have been significantly improved using electron diffraction and a refined molecular beam epitaxy growth procedure. Utilizing them in a novel structure allowed the variation of the electron density over a wide range, with peak mobilities of 4×105 cm2/V s. The continuously variable electron density allowed comparison to a theoretical analysis of the low‐temperature scattering mechanisms, and their relation to the growth process, establishing the importance of interface charges and roughness. High‐mobility samples were used to observe the quantum Hall effect with varying carrier concentrations in a single structure.