J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 1 NANOTECHNOLOGY Part 2. Electronics The Semiconductor Roadmap Energy Quantization and Quantum Dots Conductance Quantization Molecular Electronics Scanning Tunneling Microscopy

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 2 The Semiconductor Roadmap The SIA (Semiconductor Industry Association) roadmap projects a continuing miniaturization of silicon semiconductor devices for the next 15 years. International Technology Roadmap for Semiconductors (ITRS): public.itrs.net

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 3 Moore's Law Gordon Moore, co-founder of Intel, 1965 dot.che.gatech.edu Hg arc lamp 0 =436, 365, 248 nm, KrF laser 0 =248 nm, ArF laser 0 =193 nm, F 2 laser 0 =157 nm

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 4 Future Lithography Systems Synchrotron radiation based lithography Lawrence Berkeley National Laboratory (2002) Prcatically all materials absorb strongly between =157 and 14 nm Extreme UV laser based plasma sources =10-14 nm, mirrors, reflection masks X-rayX-ray tube, synchrotron ~1 nm, Fresnel lenses Ion projection, (Focused Ion Beam) EUV lithography unit oemagazine.com

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 5 Electronic Elements: Challenges scaling rules gate dielectric silicon-dioxide ~ 1.5 nm => high-k materials as Al 2 O 3, TiO 2,... dopant fluctuations, noise thermodynamics quantum effects: discretization and tunneling logic circuit architecture www-hpc.jpl.nasa.gov

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 6 Possible Future Directions Advanced MOSFET concepts 3D architecture Superconducting electronics Single electron devices Spintronics Quantum computing: qubits DNA computing from [3]

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 7 Energy Quantization from [2]

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 8 Quantum Dots (1) quantum dot size = the energy determining parameter Bawendi Group, MIT II-VI as CdSe, III-V as GaAs, Si, Ge,... Al e =0.36 nm GaAs e =21.2 nm 2D GaAs e =47.3 nm

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 9 Quantum Dots (2) Coloumb blockade Single electron devices, single electron transistor (SET) 'Artificial atoms' with tuneable electronic properties (simulate atom shell structure, quantum decoherence, break radial symmetry => quantum chaos, combine QD's to make artifical bulk materials,... ) Canditates for quantum computing

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 10 Quantum Dots (3) Sketch of vertical QD L.Kouwenhoven, C.Marcus, Physics World June 1998, p.35 (a) Current flow through a quantum dot structure, (b) analogon in terms of 2D circular orbits, (c) periodic table for artifical 2D atoms E add =e 2 /C+  E

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 11 Quantum Dots (4) Lateral QD on Al x Ga 1-x As / GaAs L.Kouwenhoven, C.Marcus, Physics World June 1998, p.35

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 12 Conductance Quantization 1 Unil. Leiden, NL

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 13 Conductance Quantization 2 meso.deas.harvard.edu/spm.html Thermal conductance quantization M.Worloch et al., Appl.Phys.Lett. 70, 2687 (1997)

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 14 Molecular Electronics (1) Towards the ultimate (?) miniaturization by using single organic molecules as electronic switches and storage elements electronic properties can be adjusted via the chemical structure size, speed, power consumption, cost individuals absolutely identical Hybrid molecular electronics Mono-molecular electronics

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 15 Molecular Electronics (2) Electrodes: covalent vs. van der Waals stability vs. self-organization Wires: delocalized  -systems, e.g., polyene Diodes: molecules with donor-acceptor substructure

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 16 Molecular Electronics (3) from [6] Switches and storage elements: metalstable molecules

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 17 Scanning Tunneling Microscopy (STM) 1 stm1.phys.cmu.edu Example: Si(111)7x7 6x6 nm 2 SEM image of W tip nprl.bham.ac.uk  LDOS  work function

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 18 STM (2) from [3] STM on InP Quantum corrals M.F.Crommie et al., Science 262, 218 (1993) M.F. Crommie, Surf. Rev. Lett. 2, 127 (1995)

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 19 Scanning Tunneling Spectroscopy cond-mat.phys.huji.ac.il 5 nm InAs nanoparticles

J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 20 Conclusion Conventional electronics meets its limits within 15 yrs Novel electronic device types are to be expected Molecular electronics has yet to prove its feasibility