title: Phosphorus atomic layer doping of germanium by the stacking of multiple δ layers.
abstract: In this paper we demonstrate the fabrication of multiple, narrow, and closely spaced δ-doped P layers in Ge. The P profiles are obtained by repeated phosphine adsorption onto atomically flat Ge(001) surfaces and subsequent thermal incorporation of P into the lattice. A dual-temperature epitaxial Ge overgrowth separates the layers, minimizing dopant redistribution and guaranteeing an atomically flat starting surface for each doping cycle. This technique allows P atomic layer doping in Ge and can be scaled up to an arbitrary number of doped layers maintaining atomic level control of the interface. Low sheet resistivities (280 Ω/ [symbol see text ) and high carrier densities (2 × 10(14) cm( - 2), corresponding to 7.4 × 10(19) cm( - 3)) are demonstrated at 4.2 K.
authors.affiliation: School of Physics, University of New South Wales, Sydney, NSW 2052, Australia. giordano.scappucci@unsw.edu.au
authors.forename: G
authors.initials: G
authors.lastname: Scappucci
authors.forename: G
authors.initials: G
authors.lastname: Capellini
authors.forename: W M
authors.initials: WM
authors.lastname: Klesse
authors.forename: M Y
authors.initials: MY
authors.lastname: Simmons