Preparation and study of 2-D semiconductors with Dirac type bands due to the honeycomb nanogeometry
Résumé
The interest in 2-dimensional systems with a honeycomb lattice and related Dirac-type electronic bands has exceeded the prototype graphene. We show that atomically coherent honeycomb superlattices of rocksalt (PbSe, PbTe) and zincblende (CdSe, CdTe) semiconductors can be obtained by nanocrystal self-assembly and subsequent cation exchange. These artificial graphene systems combine Dirac-type electronic bands with the beneficial properties of a semiconductor, such as the presence of a band gap and strong spin-orbit coupling; separated conduction 1S and 1P Dirac cones of considerable bandwidth (100 meV) are predicted, as well as dispersionless P-bands. We will also present the first experimental results dealing with the band structure (obtained by cryogenic STM) and the first carrier transport measurements and discuss possible applications of these high-mobility systems in single-photon detection and photovoltaic cells.