Low-magnetic-field gallium arsenide quantum hall resistance sample and preparation thereof

A low-magnetic-field gallium arsenide (GaAs) Quantum Hall Resistance sample, comprising:

• a GaAs heterojunction material, wherein the GaAs heterojunction material has a seven-layer structure including first to seventh layers sequentially stacked upwards and bonded to a surface of a GaAs substrate;
• wherein the first layer of the seven-layer structure is a GaAs isolation layer, the second layer of the seven-layer structure is gallium arsenide/aluminum gallium arsenide (GaAs/AlGaAs) superlattice layer, the third layer of the seven-layer structure is high-purity GaAs layer, the fourth layer of the seven-layer structure is a two-dimensional electron gas layer, the fifth layer of the seven-layer structure is an undoped AlxGa1-xAs isolation layer, the sixth layer of the seven-layer structure is a Si-doped AlxGa1-xAs layer, and the seventh layer of the seven-layer structure is a GaAs surface layer, and
• wherein a thickness of the undoped AlxGa1-xAs isolation layer is in a range of 10 nanometers (nm) to 30 nm, and x is in a range of 0.28 to 0.32, to match a carrier concentration of the two-dimensional electron gas layer with an expected low magnetic field of a central magnetic field, which is positively related to the carrier concentration of the two-dimensional electron gas layer, of a Quantum Hall Resistance plateau 2, and also to match the carrier concentration of the two-dimensional electron gas layer with an expected lower limit of a plateau width, which is positively related to the carrier concentration of the two-dimensional electron gas layer, of the Quantum Hall Resistance plateau 2;
• and the low magnetic field is in a range of 7 tesla (T) to 8 T, and the plateau width of the Quantum Hall Resistance plateau 2 is equal or greater than 0.6 T.