Implant into Si through a screen oxide

50 keV arsenic into silicon at 7° off the surface normal, through a 10 nm SiO₂ screen layer. The input is examples/as_50keV_si_sio2.toml:

# 50 keV arsenic into silicon through a 10 nm SiO2 screen layer.
#
# Run: lindhard run examples/as_50keV_si_sio2.toml --out out/as_50keV_si_sio2
#
# Schema: docs/cli.md. Energies are in eV, lengths in nm, angles in degrees.

[beam]
ion = "As"
energy_ev = 50000.0
tilt_deg = 7.0

# A compound needs an explicit density. 2.2 g/cm^3 is the usual handbook
# density of vitreous (amorphous) silica. The O energies have no defaults in
# the element table; the values below are illustrative model parameters,
# not recommendations.
[materials.SiO2]
density_g_cm3 = 2.2
elements = [
  { symbol = "Si", atom_fraction = 1.0 },
  { symbol = "O", atom_fraction = 2.0, e_d_ev = 20.0, e_s_ev = 2.0 },
]

[target]
substrate = "Si"

[[target.layers]]
material = "SiO2"
thickness_nm = 10.0

[physics]
potential = "zbl"
stopping = "lindhard-scharff"
free_path = "constant"
primary_cutoff_ev = 5.0
recoil_cutoff_ev = 2.0

# Applies to Si in both the screen and the substrate (illustrative value).
[physics.energies.Si]
e_d_ev = 15.0

[run]
ions = 2000
seed = 1

[tally]
depth_bin_nm = 1.0
depth_bins = 150

It shows a compound material with an explicit density, a finite layer over a substrate, and per-element energy overrides ([materials.SiO2] and [physics.energies.Si]). Run and check it with

lindhard check examples/as_50keV_si_sio2.toml
lindhard run examples/as_50keV_si_sio2.toml --out out/as_50keV_si_sio2

(or replace lindhard with cargo run --release -p lindhard-cli --). The run takes a fraction of a second.

Result

2000 histories, seed 1, 1 nm depth bins. The figure is depth_profile.csv of that run: the stopped As per incident ion per nm, against depth from the front face of the oxide. The shaded band is the screen layer.

Nearly all ions pass the oxide and stop in the Si, so the profile is the bare-Si profile shifted by the oxide’s own stopping, with the interface visible as the edge of the shaded band. The statistical error of the moments is the standard error in the table; 2000 histories is a coarse profile, chosen to keep the page quick.

What is validated, and what is an illustration

• Validated: the projected range of 50 keV As in bare amorphous Si against the Lindhard-Scharff-Schiøtt first-moment equation, on the ZBL potential and Lindhard-Scharff stopping used here (docs/validation.md, level 1, check range.as50k_si.rp). That is an internal consistency check against the theory the model implements, not a comparison with a measurement.
• Illustration only: the oxide layer, the E_d and E_s values (illustrative; the O energies have no defaults in the element table), the 7° tilt and the sputtered-atom count. The amorphous target has no channeling tail; the crystalline variant (examples/as_50keV_sio2_on_si_crystal.toml) is likewise an input capability, not a validated channeling prediction. This page is not a validated prediction of a measured profile.