Colloquium: Rasika MohottigeRasika Mohottige Department of Physics and Astrophysics University of North Dakota Grand Forks, ND
Coulomb Blockade and Negative Differential Resistance at Room Temperature
Self-assembled Quantum Dots on Si (110) Surface
Self-assembled quasi periodic Quantum Dots (QDs) were grown by depositing two monolayers of Ir (iridium) on Si (silicon) (110) surface. We investigated the physical and chemical properties of these QDs with the help of Scanning Tunneling Microscopy/Spectroscopy (STM/STS) and X-ray Photoelectron Spectroscopy (XPS). STM images showed that the surface was covered with large terraces corrugated with quasi periodic superstructure of QDs. I(V) (current (voltage)) curves measured on the QDs showed that conductance around Fermi level is highly suppressed. In addition to that the I(V) curves measured on the QDs has a plateau at approximately 1.5 V above the Fermi level indicating negative differential resistance (NDR). XPS data suggests that the terraces are made out of Ir and at the interface between Ir terraces and Si(110) surface, Ir-silicide forms. The shifts in position of Ir 4f and Si 2p peaks associated with Ir-silicide formation were comparable with the previously known bulk Ir-silicides.