Materials World Network: Electronic Doping in Semiconductor Nanocrystals

University Of Minnesota-Twin Cities, Minneapolis MN

Investigators

Abstract

This project involves a collaboration between two research groups at the University of Minnesota (UMN) and one from the University of Duisburg-Essen in Germany (UDE). The goal of the research is to synthesize and study nanometer-scale semiconductor crystallites (or nanocrystals) in which impurities (or dopants) have been incorporated by design. Even without such dopants, semiconductor nanocrystals can exhibit unusual and useful physical phenomena due to their small size. The critical role that dopants play in semiconductor devices such as the transistor provides a strong motivation to study doped semiconductor nanocrystals. Doping can also address key problems in nanocrystal applications from solar cells to bio-imaging. As semiconductor nanocrystals already have commercial applications (e.g., in bio-imaging) and more on the horizon (e.g., tunable lasers, light emitting diodes, and solar cells), the research should provide further control over the properties of a useful class of materials. The collaboration includes researchers at UMN who are experts in solution-based synthesis of nanocrystals and at UDE who are experts in the chemical vapor synthesis of nanocrystals and their characterization using the extended X-ray absorption fine structure (EXAFS) technique. Project objectives include (i) the development of solution- and chemical-vapor-synthetic-methods to prepare doped nanocrystals and (ii) the use of EXAFS in conjunction with reverse Monte Carlo (RMC) simulations to determine the location of the dopant. A better understanding of the doping process should result. In addition to the scientific goals, a major aim of this Materials World Network project is to provide future scientists with unique international research experiences. Students with such experiences benefit firsthand from observing how science bridges international differences. During the course of the project, 6 undergraduates and three graduate students from UMN will travel to Germany to perform research at UDE. For the undergraduate students, this will be incorporated into a research abroad summer program. For the graduate students, this can be arranged at a convenient time during their thesis project. Similarly, students from UDE will travel to UMN. These exchanges can also be facilitated by visits of UDE researchers to the US to perform EXAFS experiments at central beam lines (e.g., at Argonne National Laboratory). These visits will allow additional interactions between team members as well as analysis of samples prepared both at UMN and UDE.