מבוא לננופיסיקה המרצה: פרופ' ברוך הורוביץ

1. מבוא לננופיסיקההמרצה: פרופ' ברוך הורוביץ נושאי הקורס תכונות של חצאי מוליכים, הנדסה של מבנה פסים, אלקטרונים וחורים, סימום אלקטרוסטטיקה של מבנים ננומטרים מוליכות חשמלית, דיפוזיה, התאבכות קוונטית ולוקליזציה מוליכות בערוצים ונוסחאות לנדאואר אפקט הול קוונטי בשני ממדים, אפקט הול שבור, מטענים שבורים נקודות קוונטיות, מחסום קולוני, טרנסיסטור חד-אלקטרוני. ספר מומלץ: Thomas Ihn, "Semiconductor Nanostructure" (3 עותקים בספריה)

2. Mesoscopic systems

3. Moore’s law (Intel founding team) • ” Transistors on one chip doubles every 18 months”

4. The Development of Semiconductor Industry 1. The first transistor • W. Shockley, J. Bardeen, W. Brattain, Bell Laboratories (1947) • The first transistor Nobel Prize, 1956. 108 transistors/chips IBM 2003 Silicon flakes

5. Quartz sand → Si single cristal (2m x 20cm) Lattice defects: 1000/cm3 Defect concentration: 10-12

6. The Development of Semiconductor Industry 2. IC (Integrated Circuit) CCD (Charge Coupled Device) High Electron Mobility Transistor 600GHz max. frequency telekommunication Semiconductor laser • Z.I. Alferov, H. Kroemer, J.St.C. Kilby – Nobel Prize 2000. • for “The Basis of Technologies of Information and Communication”

7. The technology of the semiconductor industry under extreme conditions (low temperature, high magnetic field) Actual record: • Two dimensional electron gas2DEG) • λF≈10 −100nm

8. Nanostructures Litography of Electron rays (2DEG) • AFM lithography (2DEG) Resolution: ~40nm Shuffling of atoms by tunnel microscope Nobel Prize 1986.: E. Ruska; G. Binnig & H. Rohrer, electron microscope - or sweeping tunnel microscope

9. „Leave it to Nature” Self organizing structures

10. Coherent conducting phenomena Aharonov-Bohmeffect Quantifying conductivity

11. The noise as sign T is the transmission probability through a point contact. 0<T<1 has noise „The noise is the signal” R. Landauer

12. The Quantum Hall effect Klaus von Klitzing – Nobel Prize 1985. fraction number Quantum Hall effect Composite fermions H. Störmer, D.C. Tsui, R.B. Laughlin – Nobel Prize, 1998.

13. Superconducting nanostructures ,Andreev reflection -Gauging Spin polarization by Andreev spectroscopia Phenomena of interference in diffusive NS contacts

14. Quantum dots Chargingenergy

15. Atomic size molecular contact examined by nanophysics Caracteristis of conductivity in single-atom and molecular contacts - Quantifying conductivity - Fluctuating conductivity - Shotnoise - Subgap structure - Dinamic Coulomb blocade - Spetroscopy of inelastic inductivity

16. Semiconductors Basic semiconductors: Si, Ge III-V Semiconductors: GaAs, AlAs, InAs, InSb, GaSb, GaP, AlSb, InP II-IV, IV-VI semiconductors • direct gap→→ indirect gap! Applications in optics (semiconductor laser, photodetector)

17. Band engineering Band is continuously changed and mixed e.g. AlxGa1-xAs GaAs, AlAs, AlxGa1-xAs < 0.15% deviation ↓ In the lattice constant Epitaxial growth is possible on each other

18. Epitaxial growth 1. MBE, Molecular Beam Epitaxy Organised growth of atomic layers on each other Chambers to evaporate different types of materials Heated substrate; By diffusion the atoms find their favourable lattice highvacuum~ 10-10-10-11mbar Low growth: ~ 1 atomic layer/s

19. Epitaxial growth 2. In situ analysis: e.g. RHEED (Reflected High-Energy Electron Diffraction) The intensity periodically oscillates in the process of growth, so the atomic layers can be controled. The MBE is a perfect tool for growing heterostructures. The composition, thickness and doping of the layers can be varied arbitrarily

20. 2DEG GaAs-AlGaAsin heterostructure • n-AlGaAsGaAs

21. Remote doping - modulation doping Doping in GaAs: Ga -> Si (n type donor) Application: High Electron Mobility Transistor 600GHz max fequency The donor atoms have been removed from the layer of electron gas • → Exceptional mobility!

22. Formation of nanostructures /methods of growing „Cleaved egde overgrowth” 1D quantum conduction

23. Formation of nanostructures /latexial structuring Photolitography> 100nm) Structuring semiconducting layers Example: preparation of Hall sample Forming gate eletrodes

24. Formation of nanostructures /lateral structuring AFM litography Contact of quantum dots On the surface of semiconductors at room temperature a thin water layer is formed by precise control of vapour DopedSi needle+ high voltage-> Lines of oxides can be made on the surface (width<100nm, height 20-30nm) The 2DEG is removed on the oxide lines quantum dot