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Exciton lifetime measurements on single silicon quantum dots
Fatemeh Sangghaleh1, Benjamin Bruhn, Torsten Schmidt
1Materials and Nano Physics, School of ICT, KTH Royal Institute of Technology, SE-164 40 Kista, Sweden. fatsan@kth.se
Nanotechnology
|May 7, 2013
Summary
Single silicon quantum dots exhibit varying exciton lifetimes, even at the same emission energy. This dot-to-dot variation may explain non-exponential decays seen in ensemble measurements of these quantum systems.
Area of Science:
- Quantum dot research
- Solid-state physics
- Optoelectronics
Background:
- Silicon quantum dots are promising for quantum technologies.
- Understanding exciton dynamics is crucial for device performance.
- Ensemble measurements often show complex, non-exponential photoluminescence decays.
Purpose of the Study:
- To investigate the exciton lifetime of individual silicon quantum dots.
- To determine the cause of variations in photoluminescence decay times.
- To correlate single-dot behavior with ensemble measurement observations.
Main Methods:
- Fabrication of single silicon quantum dots using electron beam lithography, reactive ion etching, and oxidation.
- Measurement of photoluminescence decay curves for individual quantum dots.
- Analysis of decay characteristics, including mono-exponential behavior and lifetime variations.
Main Results:
- Observed mono-exponential photoluminescence decays for single silicon quantum dots.
- Documented a significant variation in exciton lifetimes (5-45 μs) between individual dots.
- Found that lifetime variations persist even for dots emitting at the same energy.
Conclusions:
- Single silicon quantum dot exciton lifetimes vary considerably from dot to dot.
- This intrinsic variation is a likely explanation for the non-exponential decays observed in ensemble measurements.
- Findings provide insight into the fundamental photophysics of silicon quantum dots.
