Time-Resolved Nonlinear Optical Spectroscopy of Semiconductor Interfaces

Summary

Time-resolved nonlinear optical spectroscopies are employed to obtain interface-specific information about electronic structure, vibrational excitations and  ultrafast dynamics of charge-transfer processes at semiconductor interfaces. Ongoing studies of GaP/Si(001) as a model for an interface between a polar and a nonpolar inorganic semiconductor will be continued and extended to GaAs/Ge(001). Build-up and decay of transient electric fields following optical excitation at buried interfaces is investigated with optical second-harmonic generation (SHG). Coherent phonon and plasmon dynamics of the systems are studied together with the groups of Petek (University of Pittsburgh/USA) and Ishioka (NIMS, Tsukuba/Japan) as associated partners of this CRC. A new SHG microscopy setup allows to time-resolve charge-transfer processes at interfaces between two-dimensional semiconductors, particularly as a function of their stacking angle. Finally, the dynamics of charge injection from organic thin films into silicon will be studied for well-defined interfaces based on functionalized cyclooctynes.

Project-related publications

1. K. Ishioka, A. Rustagi, A. Beyer, W. Stolz, K. Volz, U. Höfer, H. Petek, C. Stanton
   Sub-picosecond acoustic pulses at buried GaP/Si interfaces
   Appl. Phys. Lett. 111, 062105 (2017).
2. K. Brixius, A. Beyer, G. Mette, J. Güdde, M. Dürr, W. Stolz, K. Volz, U. Höfer
   Second-harmonic generation as a probe for structural and electronic properties of buried GaP/Si(001) interfaces
   J. Phys.: Condens. Matter 30, 484001 (2018) – Special Issue on Internal Interfaces.
3. J.E. Zimmermann, B. Li, J.C. Hone, U. Höfer, G. Mette
   Second-harmonic imaging microscopy for time-resolved investigations of transition metal dichalcogenides
   J. Phys.: Condens. Matter 32, 485901 (2020).
4. G. Mette, J.E. Zimmermann, A. Lerch, K. Brixius, J. Güdde, A. Beyer, M. Dürr, K. Volz, W. Stolz, U. Höfer
   Femtosecond time-resolved nonlinear optical spectroscopy of charge transfer at the buried GaP/Si(001) interface
   Appl. Phys. Lett. 117, 081602 (2020).
5. J.E. Zimmermann, Y.D. Kim, J.C. Hone, U. Höfer, G. Mette
   Directional ultrafast charge transfer in a WSe₂/MoSe₂ heterostructure selectively probed by time-resolved SHG imaging microscopy
   Nanoscale Horiz. 5, 1603 (2020).