Electrodeposited Quantum Dots: Metastable Rocksalt CdSe Nanocrystals on {111} Gold Alloys

Abstract

Thin layers of epitaxial CdSe nanocrystals with rocksalt structure have been electrodeposited onto gold alloy films. The rocksalt phase does not normally exist for CdSe at ambient pressure, and its (meta)‐stability is attributed to the strong interaction between CdSe and Cd–Au (since the phase is virtually absent for deposition onto pure gold films), and to the compressive surface tension forces of the very thin crystals. As the deposition continues, the crystals undergo a solid–solid phase transition to the more stable zincblende and wurtzite phases.

Deposition of CdSe by EC-ALE

“…However, studies of Cd upd via STM have shown this deposition feature to result in only about 1 2 the Cd coverage needed to form an ML of CdSe. A more negative potential for the deposition of Cd could be used, but potentials below about À0.5 V have been shown to result in formation of a surface alloy with the Au [19,20]. For this reason, the Cd deposition potential was held positive of À0.5 V, at least for the first few cycles.…”

Electrodeposition of patterned CdSe nanocrystal films using thermally charged nanocrystals

“…These charged particles can be locally and selectively transported to the surface for spatially controllable assembly using patterned electrodes. This method differs from the electrophoretic deposition of an ordered monolayer of micron-size latex spheres and smaller particles, [5][6][7] direct electrochemical formation of nanoparticles, 8 and more conventional electrophoretic deposition of particles, which is usually in polar solvents with particles without organic ligand capping and where films are formed on one electrode with bulklike density. 9,10 CdSe nanocrystals were prepared according to the methods of Ref.…”