P5: Excited-carrier dynamics in atomically thin 2D semiconductor

Supervision: Frank Jahnke, Gerd Czycholl

Motivation and state of the art:

Atomically thin semiconductors have many potential applications as a novel active material in electronic and optoelectronic devices like transistors, LEDs, or solar cells. A key aspect in these applications is the presence of excited carriers and their non-equilibrium dynamics, which is governed by carrier-carrier and carrier-phonon scattering processes.

Own work:

For monolayers of MoS2 we have developed a combination of ab-initio electronic state calculations (providing band structure and interaction matrix elements) with many-body theory describing various interaction processes of excited carriers. On these grounds, optical properties like absorption and photoluminescence spectra in the presence of excited carriers have been determined.

Aims and work plan:

The goal of this project is to develop a microscopic picture for the role of carrier-phonon interaction on the excited carrier dynamics in various two-dimensional materials. Scattering rates will be determined and the influence of nonequilibrium phonons will be analyzed. For this purpose, a connection will be established between ab-initio calculations of electronic states, phonon band structure, and carrier-phonon interaction matrix elements on the one hand, and a nonequilibrium many-body theory for the excited carrier dynamics on the other hand. Band structure and interaction matrix elements will be obtained in close collaboration with partners of projects P2 and P4 (based on DFT) and from P9 (using TD-DFTB).