Electronic structure of quantum dots

Kristopher Andersen, University of California, Davis

Semiconductor quantum dots are nanocrystallites with diameters in the range of 1-3 nm containing on the order of 1000 atoms. Unlike crystals, the electronic and optical properties of quantum dots are size dependent, which leads to the phenomenon that many characteristics of these materials, such as the band gap, can be “tuned” by controlling how they are grown. Although quantum dots have been intensely studied for over a decade, how the surface of the quantum dot quantitatively affects its electronic properties isn't well understood. First-principles electronic structure calculations, such as those within the framework of density-functional theory, have the potential to address these issues. However, due to the large number of atoms involved, these calculations are only possible for small systems containing on the order of 100 atoms. Here, we present a comparison of the electronic structure of quantum dots, containing less than 100 atoms, composed of Cd, Zn, and Se II-VI semiconductor compounds. The density of states and charge density is used to characterize the electronic states and contrast how these states change with the size and surface composition of the quantum dot.

Abstract Author(s): K. E. Andersen and W. E. Pickett