Surface dynamics during molecular-beam epitaxy of (In,Ga)As on GaAs(331)B: Formation of quantum wires with low In content

In_0.2Ga_0.8As molecular-beam heteroepitaxial growth on GaAs(331)B was investigated by scanning tunneling microscopy. While GaAs(331)B homoepitaxial growth always leads to a faceted ridgelike surface, In_0.2Ga_0.8As growth over this surface can lead to either wirelike corrugations or a flat surface depending on growth parameters. The transition between the phases of wirelike corrugations and a flat surface is reversible, indicating that both phases are thermodynamic favored at different temperatures. Based on this observation, we also demonstrate a novel approach for the fabrication of (In,Ga)As quantum wires in the GaAs matrix with low In contents. The carriers are confined to one-dimensional quantum wires in the In_0.2Ga_0.8As layer bounded by a lower corrugated In_0.2Ga_0.8As-on-GaAs interface and an upper flat GaAs-on-In_0.2Ga_0.8As interface.