Delta(δ)-doping of semiconductor nanowires

Abstract

The electronic sub-band structure of single δ-layers in GaAs nanowires have been determined via the self-consistent solution of the Poisson-Schrödinger equations in the effective mass approximation. The spread and sheet density of the δ-layer were varied systematically between 1-12 nm and 1012-1013 cm-2, respectively. A V-shaped potential is obtained for a δ-layer of 8 nm with a sheet density of 8 × 1012 cm-2at the core resulting in strong confinement with just one sub-band falling below the Fermi level, but complete depletion occurs for smaller spreads and/or sheet densities. In contrast a W-like potential is obtained across the diameter with three sub-bands below the Fermi level when the same δ-layer is positioned half way between the core and surface due to weaker quantum confinement. Finally, δ-doping at the surface results in a flat-band potential extending from the core up to the surface and a thinner tunnel barrier suitable for the formation of low-resistance ohmic contacts and higher carrier mobilities since the charge distribution has a maximum at the core in all of the aforementioned cases. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.