Electronic transport in colloidal II-VI nanoplatelets and nanorods

• Applicant: Dr. Alexander Achtstein
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2014 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 265219982

This project aims to investigate the transport properties of a new class of quantum wells, the freestanding, colloidal CdSe quantum wells also called nanoplatelets. The intention of this application is to make it possible to introduce the applicant into a new research discipline, in this case terahertz and microwave transport measurements in nanoscale materials. These techniques allow for the measurements of true carrier mobilities in nanoscopic systems, which are not superimposed by properties of electrical contacts, tunnel barriers or strain at the interfaces. The carrier and exciton mobilities in II-VI nanorods and nanoplatelets shall be investigated. Also the question if the generated charge carriers upon optical excitation are present in the nanoplatelets as excitons or unbound electron-hole pairs will be addressed in this project. These properties shall be investigated in metal chalcogenide nanorods and nanoplates (CdSe, CdS, PbS).The investigations shall take place in the host group of Prof. Siebbeles at Delft University of Technology, who has outstanding expertise in terahertz and microwave conductivity measurements and in the provision of scientific mentoring to research fellows. The proposed investigations concentrate on the measurement of the charge mobility in these nanoparticles with respect to the size and shape dependence, the composition dependence and the influence of phonon scattering on the charge mobility. In a second step the nature of the photo-excited state shall be investigated. Here it is planned to investigate, if the majority of excited carriers are present in the form of excitons or free electron hole pairs. This question will be addressed by a detailed analysis of the real and imaginary parts of the complex terahertz and microwave conductivity.

• DFG Programme: Research Fellowships
• International Connection: Netherlands
• Host: Professor Dr. Laurens Siebbeles