Insulator-quantum Hall transitions in two-dimensional electron gas containing self-assembled InAs dots

We present a study of magnetotransport properties in two-dimensional electron gases formed in a GaAs/Al0.33Ga0.67As quantum well, where self-assembled InAs quantum dots have been inserted into the centre of the GaAs well. In a perpendicular magnetic field there are transitions between quantum Hall liquids at filling factors ν=2 and 1 and the insulating phase from temperature independent points. In the insulating regime we observe ν=4 and 6 quantum Hall states due to Landau quantisation. We are able to construct a phase diagram in which Shubnikov–de Haas oscillations and insulating behaviour coexist.