Comsol Simulations

Comsol SimulationsEdit

2014-01

Update on geometry given by lithography
- Reproduce geometry in dxf format (under klayout + layout editor)
- import it in comsol (polygons only, not paths)
- define a small box 400nm thickness in z direction around the small patterns (boundary condition: continuity) to ease the meshing procedure
- define a big box 50µm x 100µm x 20µm
- extrude designs to 50nm for the small patterns, 150nm for the Nb resonator

Mesh first the patterns in the small box, as fine as wished
Then mesh the remaining with at least 2 levels coarser

First simulation on 145000 dof, ~25s. Potentials set to -0.5V, except for island +0.5V.

- Boundary Integration of the surface charge
C_island (total) = 0.725 fF (have to add the overlap capacitance, ~100 aF per junction)
C_gate res = 0.2 fF
C_gate det = 0.18 fF
C_gate feedback = 0.15 fF
C_resonator pads = 0.14 fF
C_JJ (pattern above island) = 0.09 fF

-> Total capacitance to resonator : 0.2 + 0.14 + 0.09 = 0.43fF
-> Total island capacitance : 0.925 fF