Asymmetric double two-dimensional electron gas structures for electrical quantum metrology

We study growth and low temperature magnetotransport of Ga(Al)As based asymmetric double two-dimensional electron gas (2DEG) structures consisting of a quantum well stacked on top of a heterojunction. These structures allow for matching the electron densities in the two parallel 2DEGs by variation of a single growth parameter without the appearance of any parasitic transport channel. At filling factor 2, we observe a 2 T wide quantum Hall plateau of metrological quality with a quantized resistance of one quarter of the resistance quantum. Such structures can be used for electrical quantum metrology and to fabricate vertically integrated circuits.