Quantum Hall Effect in Wide Parabolic GaAs/Al_xGa_1−xAs Wells

Abstract

The ability to produce narrow two-dimensional (2D) layers of high mobility electron gas in semiconductor structures has permitted the study of the 2D electron gas in strong magnetic fields under nearly ideal conditions, and led to the discovery of the integer and fractional quantum Hall effects [1]. Despite many interesting experiments, comparable progress has not been made for the three dimensional (3D) electron gas in semiconductors, due in part to the strong influence of the potential from dopant atoms. Remotely-doped parabolic GaAs/A1_xGa_1−xAs wells can be used to produce relatively thick (>1000 Å) layers of high mobility electron gas [2, 3] which are spatially uniform due to the action of the parabolic potential. We report here high magnetic field measurements of both the 2D integer and fractional quantum Hall effects for a partially-filled wide parabolic GaAs/Al_xGa_1−xAs well [2] with very high low temperature mobility µ = 2.5x10⁵ cm²/Vsec. These measurements demonstrate both the feasibility of the parabolic well technique and the high quality of the structures.