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Understanding Quantum Transport in Semiconductor Nanostructures

Explore electron states in nanostructures, conductance concepts, and quantum transport phenomena. Dive into 2D, 1D, and 0D structures like graphene, carbon nanotubes, and more. Learn about electron effective mass, Schrödinger equation, and density of states in different dimensions.

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Understanding Quantum Transport in Semiconductor Nanostructures

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  1. Katherine Luna, Inspiration [online image] 23 Feb 2011, http://www.lorentz.leidenuniv.nl/inspiration/

  2. Quantum transport in semiconductor nanostructures Thomas Ihn ETH Zürich FS 2017

  3. Organisation Exercise classes: Hiske Overweg, overwegh@phys.ethz.ch Riccardo Pisoni, pisonir@phys.ethz.ch What you are supposed to do: • 1 oral presentation (10 min) in the exercise class • solve the problem sheets • active participation in lecture and exercise class (!) Website: http://www.nanophys.ethz.ch

  4. Feedback... please feed back!

  5. Today's lecture • Nanostructures in 2D – 1D – 0D • How we describe electron states • What is conductance really?

  6. Nanostructures in 2D - 1D - 0D

  7. Nanostructures in 2D - 1D - 0D A.H. Castro Neto et al, Drawig conclusions from Graphene, Physics World (Nov 2006) [online], 22 Feb 2012, http://physics.bu.edu/~neto/Topic0.htm

  8. Electrons in two dimensions

  9. Electrons in two dimensions

  10. Electrons in two dimensions 2004: • 90 nm technology • smallest gate length 50 nm • 5x106 transistors/chip Si wafer IBM Switching speed: • channel length • drift velocity Pentium IV: • 42’000’000 transistors • 2 GHz strained-silicon transistor (IBM)

  11. Electrons in one dimension Carbon nanotubes

  12. Electrons in one dimension InAs nanowires Bi2Se3 nanoribbons: topological insulators

  13. Electrons in one dimension Graphene nanoribbons

  14. Electrons in one dimension GaAs quantum point contacts GaAs quantum wires by cleaved edge overgrowth

  15. Electrons in zero dimensions AFM- lithography electron beam lithography growth on prepatterned substrates+self-assembly self-assembling growth

  16. How we describe electron states

  17. Band structure of GaAs and Si GaAs Si

  18. Effective mass approximation (parabolic band) Quantum description: Schrödinger • Effective mass • Envelope functions Corresponding classical description: Newton

  19. Our simplified quantum view on electrons effective mass Schrödinger equation

  20. Density of states in 2D, 1D, and 0D

  21. Quantum transport phenomena 1987 1980 1989 1980

  22. What is conductance?

  23. Trajectory picture of electron transport

  24. Read until next week Chapters VI. Fabrication of nanostructures X.1-3 Drude model

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