page_title: Superlattice
section_title: Semiconductor materials
hierarchical_section_title: Superlattice / Semiconductor materials
caption_attribution_description: English: GaAs/AlAs superlattice and potential profile of conduction and valence bands along the growth direction (z). Русский: Сверхрешётка GaAs-AlAs и энергии валентной зоны и зоны проводимости.
context_page_description: A superlattice is a periodic structure of layers of two materials. Typically, the thickness of one layer is several nanometers. It can also refer to a lower-dimensional structure such as an array of quantum dots or quantum wires.
context_section_description: Semiconductor materials, which are used to fabricate the superlattice structures, may be divided by the element groups, IV, III-V and II-VI. While group III-V semiconductors (especially GaAs/AlₓGa1−xAs) have been extensively studied, group IV heterostructures such as the SiₓGe1−x system are much more difficult to realize because of the large lattice mismatch. Nevertheless, the strain modification of the subband structures is interesting in these quantum structures and has attracted much attention.
  In the GaAs/AlAs system both the difference in lattice constant between GaAs and AlAs and the difference of their thermal expansion coefficient are small. Thus, the remaining strain at room temperature can be minimized after cooling from epitaxial growth temperatures. The first compositional superlattice was realized using the GaAs/AlₓGa1−xAs material system.
  A graphene/boron nitride system forms a semiconductor superlattice once the two crystals are aligned. Its charge carriers move perpendicular to the electric field, with little energy dissipation. h-BN has a hexagonal structure similar to graphene's. The superlattice has broken inversion symmetry. Locally, topological currents are comparable in strength to the applied current, indicating large valley-Hall angles.
caption: GaAs/AlAs superlattice and potential profile of conduction and valence bands along the growth direction (z).
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