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Quantum transport in semiconductor nanostructures

Quantum transport in semiconductor nanostructures. Thomas Ihn ETH Zürich FS 15. Trajectory picture of electron transport. y. applied voltage. Number of modes. Conductance quantum. Transmission (0 or 1). Directed current flow in resistors. Last week: (Semi)classical conductivity.

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Quantum transport in semiconductor nanostructures

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  1. Quantum transport in semiconductor nanostructures Thomas Ihn ETH Zürich FS 15

  2. Trajectory picture of electron transport y applied voltage Number of modes Conductance quantum Transmission (0 or 1)

  3. Directed current flow in resistors Last week: (Semi)classical conductivity Metal film resistors Resistive metal wire How small can a resistor be made?

  4. Is there an "elementary" resistor? Thales of Miletus, about 600 B.C. rubbing amber with fur: the birth of electricity Demokritus, about 460 B.C. break a piece of matter in half, then in half again, and so on: is there a smallest unit? Idea dismissed by Aristotle, picked up again more than 2000 years later in 1800 by Dalton

  5. One-dimensional conductors:the ultimate nanoresistors Carbon nanotubes

  6. One-dimensional conductors:the ultimate nanoresistors InAs nanowires Bi2Se3 nanoribbons: topological insulators

  7. One-dimensional conductors:the ultimate nanoresistors Graphene nanoribbons

  8. One-dimensional conductors:the ultimate nanoresistors GaAs quantum point contacts GaAs quantum wires by cleaved edge overgrowth

  9. Conductance of graphene nanoribbons Susanne Dröscher, ETHZ, 2011 Irregular resonances

  10. Conductance of GaAs nanowires U. Meirav, M.A. Kastner, PRB 40, 5871 (1989) Periodic resonances

  11. Conductance of a constrictionin a GaAs 2D electron gas dg/dVG Clemens Rössler, ETHZ, 2010 Step-like conductance increase in units of 2e2/h

  12. Conductance quantization The pioneering work Van Wees et al., 1988 Step-like increase of the conductance

  13. Landauer-Büttiker theory Markus Büttiker Rolf Landauer (1927-1999)

  14. Read until next week Chapter XI.1–7 Ballistic electron transport in QPCs

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