Confinement, overflow, and emission of holes on SiGe surface with Ge dots: Heterogeneous hole redistribution and its application to virtual dot manipulation

Abstract

The hole confinement in Ge dots fabricated on a wetting layer in Stranski–Krastanov (S-K) growth was directed by an applied bias. At medium bias voltage, the holes overflowed from the small dots, indicating a moderate potential barrier without a notch at the boundary. The electrostatic force of the confined holes attracted excessive holes to the wetting layer. The system was energetically stabilized by the formation of a “virtual dot” in an open space enclosed by dots. At a high bias voltage, the virtual dot disappeared since the holes in the wetting layer were emitted from the surface.