Band-Edge Diagrams of Core−Shell Semiconductor Dots

We have calculated band-edge diagrams for spherical core−shell nanocrystal quantum dots for all combinations of AlN, GaN, and InN, as well as all combinations of AlP, GaP, AlAs, GaAs, InP, InAs, AlSb, GaSb, and InSb, as a function of core radius, with the outer radius of the shell held fixed. We have calculated the Γ- and the X-conduction band minima, the valence band maximum, and the effective masses using strain-dependent eight-band kp theory, with a linear continuum model for the strain. We have found all the band alignments that may occur, and identified all combinations where one material becomes metallic due to a negative gap. Structures which are suitable for biological applications have been identified. We provide a figure which allows easy calculation of the confinement energy using a single band model.