Band offsets, wells, and barriers at nanoscale semiconductor heterojunctions

Y.M. Niquet (1, 2) , C. Delerue (3)

1 LSIM - Laboratory of Atomistic Simulation
2 SP2M - UMR 9002 - Service de Physique des Matériaux et Microstructures
3 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520

Epitaxially grown semiconductor heterostructures make it possible to tailor the potential landscape for the carriers in a very controlled way. In planar lattice-matched heterostructures, the potential has indeed a very simple and easily predictable behavior: it is constant everywhere except at the interfaces, where there is a step (discontinuity) that only depends on the composition of the semiconductors in contact. In this paper, we show that this universally accepted picture can be invalid in nanoscale heterostructures (e.g., quantum dots, rods, nanowires), which can presently be fabricated in a large variety of forms. Self-consistent tight-binding calculations applied to systems containing up to 75 000 atoms indeed demonstrate that the potential may have a more complex behavior in axial heteronanostructures: The band edges can show significant variations far from the interfaces if the nanostructures are not capped with a homogeneous shell. These results suggest new strategies to engineer the electronic properties of nanoscale objects, e.g., for sensors and photovoltaics.

Domaines: Micro et nanotechnologies/Microélectronique

Y.M. Niquet, C. Delerue. Band offsets, wells, and barriers at nanoscale semiconductor heterojunctions. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2011, 84 (7), pp.075478. ⟨10.1103/PhysRevB.84.075478⟩. ⟨hal-00639883⟩