SINGLE-ELECTRON TRANSISTORS WITH A SELF-ASSEMBLED QUANTUM-DOT

Single-electron transistors with a self-assembled quantum dot are fabr icated by direct epitaxial growth on patterned substrates. A serf-asse mbled quantum dot is formed during the deposition of an AlxGa1-xAs/GaA s heterostructure on a bow-tie-shaped constriction, pre-patterned on a GaAs substrate. The self-assembled quantum dot is located in the cent re of the constriction and is coupled via tunnelling barriers, also fa bricated within the same growth process, to electrical leads. The fabr icated devices allow switching with single electrons up to temperature s of 6 K by applying a voltage to an in-plane gate, which is also fabr icated during the epitaxial growth. The structure of the devices is al so characterized using scanning-electron and atomic-force microscopy.