Focused Electron Beam Induced Deposition: 3D Nanowire Growth

Beam Scan Mode

Beam & Precursor

Electron beam current J_e 1.20

Precursor gas flux J_gas 1.00

Surface diffusion D 1.50

Precursor Coverage Under Beam

θ = 0%—

Live Readouts

Growth rate

0.0 /s

Beam-on time

0.0 s

Total deposited mass

0.0

Mass / beam-on time

0.0

How it works

This 2D cross-section models the same FEBID physics as the 3D wire grower, but here the precursor coverage is a real spatial field θ(x,y,t) that diffuses across the substrate instead of one shared number. Wherever the beam dwells it locally dissociates adsorbed precursor and deposits solid material; away from the beam, precursor slowly re-adsorbs from the ambient gas and diffuses in from neighbouring, less-depleted cells.

∂θ/∂x,y,t = D·∇²θ + a·(1-θ) − b·θ·beam(x,y,t)
a = s·J_gas   (ambient adsorption / replenishment)
b = σ·J_e     (beam dissociation, applied only under the beam)
deposit rate at (x,y) = b·θ(x,y)·beam(x,y,t)   → consumes θ locally as it accumulates

Manual draw — click-drag across the canvas to steer the beam yourself, e.g. tracing a straight vertical tip-growth path like a real nanowire write.
Auto: fast scan — the beam sweeps rapidly back and forth over a row of points, giving each point many short exposures with idle gaps in between, during which θ diffuses back up before the beam returns.
Auto: slow dwell — the beam completes one long, uninterrupted dwell at each point before moving to the next, at the same total beam-on time per point as the fast scan.
Compare button — fast-forwards both scan strategies through the identical finite-difference kernel used on screen and reports the actual total deposited mass of each. Fast, repeatedly-interrupted scanning consistently deposits more total mass than one long dwell at the same beam-on time, because continuous dwelling drains θ toward its local, diffusion-starved equilibrium and stays there, while interrupted scanning keeps letting θ recover — this is the diffusion-limited-vs-reaction-limited tradeoff real FEBID operators manage with multi-pass low-dose raster strategies.

Click and drag on the substrate to steer the electron beam and grow material.

Vacuum / bare substrate Precursor-rich gas (high θ) Deposited solid Electron beam