Density functional theory in the LDA+U approximation is used to calculate the electronic structure of germanium δ-doped with phosphorus and arsenic. We characterize the principal band minima of the two-dimensional electron gas created by δ-doping and their dependence on the dopant concentration. Populated first at low concentrations is a set of band minima at the perpendicular projection of the bulk conduction band minima at L into the (kx,ky) plane. At higher concentrations band minima at Γ and Δ become involved. Valley splittings and effective masses are computed using an explicit-atom approach, taking into account the effects of disorder in the arrangement of dopant atoms in the δ-plane.
Carter, D.j., Warschkow, O., Gale, J.d., Scappucci, G., Klesse, W.m., Capellini, G., et al. (2013). Electronic structure of phosphorus and arsenic δ-doped germanium. PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS, 88 [10.1103/PhysRevB.88.115203].