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Nanofabrication of Gate-defined GaAs/AlGaAs Lateral Quantum Dots
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Hot-electron dynamics in quantum dots manipulated by spin-exchange Auger interactions
Rohan Singh1, Wenyong Liu1, Jaehoon Lim1,2,3
1Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
Nature Nanotechnology
|October 9, 2019
Summary
Magnetically doped quantum dots enable efficient
Area of Science:
- Semiconductor physics
- Quantum dot applications
- Energy conversion technologies
Background:
- Non-equilibrium 'hot' carriers offer potential for efficient energy harvesting.
- Fast intraband cooling in semiconductors via phonon emission hinders hot-carrier schemes.
- Current energy transfer mechanisms are often outpaced by energy dissipation.
Purpose of the Study:
- To investigate methods for overcoming fast intraband cooling in semiconductor quantum dots.
- To explore novel energy transfer mechanisms for hot carriers.
- To demonstrate efficient 'uphill' energy transfer exceeding cooling rates.
Main Methods:
- Utilizing magnetically doped colloidal semiconductor quantum dots.
- Investigating spin-exchange processes for energy transfer.
- Comparing energy gain rates from spin-exchange with intraband cooling rates.
Main Results:
- Achieved extremely fast spin-exchange rates in magnetically doped quantum dots.
- Demonstrated 'uphill' energy transfer with rates significantly exceeding intraband cooling.
- Observed an energy gain/loss rate ratio at least three times more favorable than standard Auger-type transfer.
- Showcased the potential for spin-exchange-mediated carrier multiplication and upconversion.
Conclusions:
- Magnetically doped quantum dots facilitate highly efficient hot-carrier energy transfer.
- The favorable energy gain/loss ratio enables novel hot-carrier energy harvesting schemes.
- This approach can lead to advancements in hot-carrier extraction and electron photoemission.
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