Impact of defects on photoexcited carrier relaxation dynamics in GeSn thin films
Abstract
We report the results of a study that was conducted to investigate the recombination paths of photoexcited charge carriers in GeSn thin films. The charge carrier lifetime was predicted as a function of temperature from a description of photoconductivity transients, assuming co-influence of Shockley–Read–Hall and radiative carrier recombination paths. We identify that dislocations are the source of a band of electronic states with the highest occupied state at E V + (85÷90) meV that acts as Shockley–Read–Hall centers determining the charge carrier lifetime. The photoluminescence (PL) and photoconductivity spectroscopy have been applied to distinguish between the contribution of both band-to-band and dislocation-related electron transitions. The PL band was found to demonstrate a low-energy shift of about 80 ± 20 meV relative to the edge of the photoconductivity spectra in the indirect bandgap GeSn films with dislocations. The role of a different nature deeper acceptor level at E V + (140 ÷ 160) meV in the recombination processes of the GeSn layers with better structural quality and the Sn content higher than 4% was discussed. This detailed understanding of the recombination processes is of critical importance for developing GeSn/Ge-based optoelectronic devices.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Feb 10, 2020
- Source ID
- 10.1088/1361-648x/abc4ce
Entities
People
- Andrian V Kuchuk
- Gregory J. Salamo
- H Stanchu
- P M Lytvyn
- S S Derenko
- S.-q. Yu
- Serhiy V Kondratenko
- V. S. Lysenko
- Yu I Mazur
Organizations
- CRDF Global