Vertical quantum wire realized with double cleaved-edge overgrowth

A quantum wire is fabricated on (001) GaAs at the intersection of two overgrown cleaves. The wire is contacted at each end to n+-GaAs layers via two-dimensional (2D) leads. A side gate controls the density of the wire revealing conductance quantization. The step height is strongly reduced from 2e2∕h due to the 2D lead series resistance. We characterize the 2D density and mobility for both cleave facets with four-point measurements. The density on the first facet is modulated by the substrate potential, depleting a 2μm wide strip that defines the wire length. Microphotoluminescence shows an extra peak consistent with one-dimensional electron states at the corner.