A hybrid Al0.10Ga0.90As/AlAs bilayer electron system with tunable g-factor

We have fabricated a device composed of two closely coupled two-dimensional electron systems, one of which resides within an AlAs quantum well at the X point of the Brillouin zone, while the other is contained at the Gamma point in the alloy Al0.10Ga0.90As, grown directly below the AlAs. The electronic properties of these two systems are strongly asymmetric: the respective cyclotron masses in the AlAs and the Al0.10Ga0.90As layers, measured in units of the free electron mass, are similar to0.5 and 0.07, while the effective electron g-factors are approximately 7 and 0. With the help of front and back gates, we can confine mobile carriers to either or both of the two quantum wells, as confirmed by magnetotransport measurements. (C) 2004 American Institute of Physics.