GoKawiilStudy finds Bi2S3 semiconductor exhibits unusually slow electron-hole recombination
Researchers used terahertz, millimetre-wave conductivity, and photoluminescence probes to track photoexcited charge carriers in bismuth sulfide (Bi2S3) thin films over timescales from 200 femtoseconds to 1 microsecond. They found that most carriers recombine within about 100 nanoseconds via defect-mediated trapping, while at higher excitation intensities and shorter picosecond timescales, an intrinsic electron-hole recombination process dominates. The team modeled these combined behaviors using a rate equation that separates defect-related and intrinsic recombination contributions.
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The findings could clarify why Bi2S3, despite having a band structure that is not fully direct, shows recombination behavior relevant to optoelectronic performance, according to the researchers' modeling approach. Understanding how trapping and intrinsic recombination interact may help guide efforts to engineer defect density in similar pseudo-direct semiconductors for solar or photodetector applications. The detailed kinetic model could also serve as a template for analyzing carrier dynamics in other unconventional semiconductor materials.
- Bi2S3 thin films show carrier recombination spanning femtoseconds to microseconds, studied via THz, mmW, and PL probes.
- Most carriers recombine within ~100 ns through defect-mediated, dispersive trapping described by a stretched exponential decay.
- A combined kinetic model separating monomolecular and bimolecular recombination was used to extract bimolecular recombination rates.
Source: nature.com — Righetto, 2026-10-28
Published there as: “Delayed electron–hole recombination in a pseudo-direct semiconductor”
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