Submicron structures 26th January 2004 msc
Condensed Matter Physics
Photolithography to ~1 μmUsed for...
Spin injection Flux line dynamics Josephson junctions SQUIDs Superconducting mesa
structuresfeaturesto 1-2 μm
Device Physics cleanroom
Submicron structures 26th January 2004 msc
Condensed Matter Physics
Opportunities below 1 μm
Higher interface resistance R simplifies interpretation. Get R > h/e2 : resistance quantum
Measure spin flip length < 1 μm
Isolate individual crystal grains/twins: directions important for d-wave superconductors
Access mesoscopic quantum behaviour: single electron, single spin, single Cooper pair
d d
300 nm
I
Submicron structures 26th January 2004 msc
Condensed Matter Physics
Focused Ion Beam fabrication
30 kV Gaion source
Focus to ~30 nm.Remove or addmaterial
Observe by SEM while writing,
select desired region of sample
University Nanotechnology Research Centre(Mechanical Engineering)
Submicron structures 26th January 2004 msc
Condensed Matter Physics
Superconducting wires to 100 nm (so far...) by FIB
Well-controlled structure
Quantum effects easily seen
6 μm photolith.270 nm FIB
Superconducting phase slip
Submicron structures 26th January 2004 msc
Condensed Matter Physics
Physics << 1 μm
Use quantum effects as a probe of electron systems – e.g. Coulomb blockade to measure energy distribution
Quantum computers motivate study of systems having quantum coherence
Combine mesoscopic conductors with intrinsic Josephson tunnelling
Submicron structures 26th January 2004 msc
Condensed Matter Physics
Our strengths
Expertise in ultrasensitive electrical measurements: - Shot noise - SQUID detectors
Well-equipped for quantum-dominated measurements: - mK temperatures - 10 T fields
Wide range of interesting material properties - HTc have energy gap > kT & charging energy - HTS have nm-scale laminar structure - Ferromagnetic, unconventional materials available
Submicron structures 26th January 2004 msc
Condensed Matter Physics