No Access Submitted: 07 January 2019 Accepted: 07 June 2019 Published Online: 20 June 2019
Appl. Phys. Lett. 114, 241104 (2019);
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  • J. Allerbeck
  • A. J. Herbst
  • Y. Yamamoto
  • G. Capellini
  • M. Virgilio
  • D. Brida
We study the femtosecond carrier dynamics of n-type doped and biaxially strained Ge-on-Si films which occurs upon impulsive photoexcitation by means of broadband near-IR transient absorption spectroscopy. The modeling of the experimental data takes into account the static donor density in a modified rate equation for the description of the temporal recombination dynamics. The measurements confirm the negligible contribution at a high n-type doping concentration, in the 1019 cm−3 range, of Auger processes as compared to defect-related Shockley-Read-Hall recombination. Energy resolved dynamics reveal further insights into the doping-related band structure changes and suggest a reshaping of direct and indirect conduction band valleys to a single effective valley along with a significant spectral broadening of the optical transitions.
This work was supported by the Emmy Noether Programm of the DFG (No. BR 5030/1-1).


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