Energy Shifts, Intensity Minima, and Line Splitting in the Optical Recombination of Electrons in the Integer and Fractional Quantum Hall Regimes

Abstract

Energy shifts in the electron-hole recombination energy and minima in the peak intensity at integer and fractional filling factors occur in the luminescence from ultra high mobility GaAs single quantum wells and heterojunctions. At Landau and spin gaps the magnetic field regions of the energy shifts and intensity minima broaden as the temperature is reduced, in consort with the transport Hall resistance. This relates the optical anomalies directly to the position of the Fermi energy in localized transport states. In the fractional quantum Hall regime a sharp intensity minimum and peak shift is observed at v = 2/3, while higher-field fractions are characterized by a splitting in the luminescence, with the higher-energy component dominant at higher fields. The response of the 2D electron gas to the perturbation of the hole is an important consideration, and is studied by varying the quantum well width, whence it is found that correlation effects are reduced relative to vertex corrections as the well width is increased.