Ab initio theory of free-carrier absorption in semiconductors
Abstract
The absorption of light by free carriers in semiconductors results in optical loss for all photon wavelengths. Since free-carrier absorption competes with optical transitions across the band gap, it also reduces the efficiency of optoelectronic devices such as solar cells because it does not generate electron-hole pairs. In this work, we develop a first-principles theory of free-carrier absorption taking into account both single-particle excitations and the collective Drude term, and we demonstrate its application to the case of doped Si. We determine the free-carrier absorption coefficient as a function of carrier concentration and we obtain excellent agreement with experimental data. We identify the dominant processes that contribute to free-carrier absorption at various photon wavelengths, and analyze the results to evaluate the impact of this loss mechanism on the efficiency of Si-based optoelectronic devices.
- Publication:
-
Physical Review B
- Pub Date:
- November 2022
- DOI:
- 10.1103/PhysRevB.106.205203
- arXiv:
- arXiv:2205.02768
- Bibcode:
- 2022PhRvB.106t5203Z
- Keywords:
-
- Condensed Matter - Materials Science;
- Physics - Optics
- E-Print:
- 8 pages, 6 figures