1 / 14

Quantum Dots

Quantum Dots. KE – 31.5530 Nanopartikkelit 4.5.2011 Lauri Lehtola. Outline. Quantum dots structure Preparation methods Applications Excisting and visionary. http://www.lbl.gov/Science-Articles/Archive/Quantum-Dot-Electronics.html. Quantum dots. Nanocystals

salvador-stanton
Télécharger la présentation

Quantum Dots

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Quantum Dots KE – 31.5530 Nanopartikkelit 4.5.2011 Lauri Lehtola

  2. Outline • Quantum dots • structure • Preparation methods • Applications • Excisting and visionary http://www.lbl.gov/Science-Articles/Archive/Quantum-Dot-Electronics.html

  3. Quantum dots • Nanocystals • Both atom and bulk-like properties • Commonly made from semiconductor materials or heavy metals • Research began in 1980s • Smaller semiconductor devices • Quantum wells (2D), quantum wires (1D) DNA 1/2

  4. Quantum Dots • Current carriers are confined in all three dimensions • Dimension size ~ electron wave length • Quantum mechanical particle in a box –situation • Solution: • Discrete energy levels

  5. Quantum Dots • Discrete energy levels • Fluorescence • Controlling of energy gaps • Small size  high gap  high energy • Different wavelengths • Tunable or ”man-made” atoms http://www.rsc.org/Publishing/ChemTech

  6. Quantum Dots • Easily in situ –alterable • Energy level structure • Modified with voltage • Magnetic phases • Controlled with external magnetic fields • Electrical, catalyst properties… • Onion-like architecture, etc. http://www.enc.edu/~john.u.free/

  7. Preparation • Chemical synthesis from colloids • Precursor, surfactant, solvent • Typical precursors: CdSe, CdS, InAs • Correct temperature and precursor concentration • Highly monodisperse particles • Commercially used method http://www.nanocotechnologies.com/

  8. Preparation • Self-assembling during molecular beam epitaxy • Quantum dots on a surface • Stranski-Krastanov growth • Certain layer thickness islands nucleate http://www-thz.physics.ox.ac.uk/publications.html

  9. Preparation • New cheaper and faster methods • Restrictions of using heavy metals • Room temperature preparation • Sonochemical Synthesis http://pubs.acs.org/doi/full/10.1021/cm0505547

  10. Applications • Solar cells • Traditional cells: excess kinetic energy • This energy is lost soon • Quantum dot coating • Multiple excitons from a single photon • MEG (Multiple Exciton Generation) http://www.nanoprinttech.com/quantum_dot.html

  11. Applications • Biological tracking • Tag molecules with quantum dots • Only particlular molecules • Processes inside living cells • Clusters of quantum dots • No blinking http://www.ieeeghn.org/wiki/index.php/Quantum_Dots

  12. Applications • QLEDs and QLED displays • Direct utilization of electroluminescence • Electrons to photons • Easy patterning • Inkjet printing • Pure colors • No color masks  smaller energy consumption • Short lifetime (10 000 h) http://www.physorg.com/news/2011-02-fabricate-large-area-full-color-quantum-dot.html

  13. Applications • Other possibilities: Quantum computer • Quantum dots as ”qubits” • ”Application”: scientific tool • Theoretical information of few-body effects in finite and reduced dimensions • Already now new phenomena • New phases, magnetic ground states • More to come

  14. Conclusion • Structure • Confined electrons and holes • Preparation • Chemical, MBE • Applications • Variety of ways to utilize

More Related