Doping Colloidal Semiconductor Nanoparticles

Andrew Wills (Chemistry), Advisors: Wayne Gladfelter (Chemistry), David Norris (CEMS)

The ability to introduce trace amounts of impurities, called dopants,  into semiconductors in the bulk is one of the main factors behind the  widespread use of semiconductors in technology today. More recently,  many scientists have begun to investigate nanoparticles. Due to their  small size, nanoparticles exhibit molecule-like quantum effects, but  their properties can be changed by varying physical parameters such  as size and crystallinity. There are many ways to dope bulk  semiconductors, but attempts to dope nanoparticles have had limited  success. My project is to understand the process of doping  nanoparticles. Understanding the principles of doping will allow us  to synthesize nanoparticles with novel properties of broad scientific  and industrial importance.

Recently, the Norris group proposed a model for nanoparticle doping  where the "stickiness" of the crystal facets determined the degree to  which dopants could be incorporated in the nanoparticle.1  My current  project is to synthesize ZnSe and CdSe nanoparticles that contain n- type dopants using a colloidal procedure and a wide variety of  characterization techniques. With luck, this work will confirm our  theory and lead to a better understanding of the doping process.

1. Erwin, S. C.; Zu, L.; Haftel, M. I.; Efros, A. L.; Kennedy, T. A.;  Norris, D. J. Nature 2005, 436, 91.