DEVSIM is an open source semiconductor device simulation software using the finite volume method to solve partial differential equations on a mesh. The solver is accessed using the python API. For more information, visit the official website.

Below is the example showing 2D capacitor simulation. The source of the example is examples folder in devsim github repository.

# Copyright 2013 Devsim LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from devsim import *
device="MyDevice"
region="MyRegion"

xmin=-25
x1  =-24.975
x2  =-2
x3  =2
x4  =24.975
xmax=25.0

ymin=0.0
y1  =0.1
y2  =0.2
y3  =0.8
y4  =0.9
ymax=50.0

create_2d_mesh(mesh=device)
add_2d_mesh_line(mesh=device, dir="y", pos=ymin, ps=0.1)
add_2d_mesh_line(mesh=device, dir="y", pos=y1  , ps=0.1)
add_2d_mesh_line(mesh=device, dir="y", pos=y2  , ps=0.1)
add_2d_mesh_line(mesh=device, dir="y", pos=y3  , ps=0.1)
add_2d_mesh_line(mesh=device, dir="y", pos=y4  , ps=0.1)
add_2d_mesh_line(mesh=device, dir="y", pos=ymax, ps=5.0)

device=device
region="air"

add_2d_mesh_line(mesh=device, dir="x", pos=xmin, ps=5)
add_2d_mesh_line(mesh=device, dir="x", pos=x1  , ps=2)
add_2d_mesh_line(mesh=device, dir="x", pos=x2  , ps=0.05)
add_2d_mesh_line(mesh=device, dir="x", pos=x3  , ps=0.05)
add_2d_mesh_line(mesh=device, dir="x", pos=x4  , ps=2)
add_2d_mesh_line(mesh=device, dir="x", pos=xmax, ps=5)

add_2d_region(mesh=device, material="gas"  , region="air", yl=ymin, yh=ymax, xl=xmin, xh=xmax)
add_2d_region(mesh=device, material="metal", region="m1" , yl=y1  , yh=y2  , xl=x1  , xh=x4)
add_2d_region(mesh=device, material="metal", region="m2" , yl=y3  , yh=y4  , xl=x2  , xh=x3)

# must be air since contacts don't have any equations
add_2d_contact(mesh=device, name="bot", region="air", yl=y1, yh=y2, xl=x1, xh=x4, material="metal")
add_2d_contact(mesh=device, name="top", region="air", yl=y3, yh=y4, xl=x2, xh=x3, material="metal")
finalize_mesh(mesh=device)
create_device(mesh=device, device=device)



###
### Set parameters on the region
###
set_parameter(device=device, region=region, name="Permittivity", value=3.9*8.85e-14)

###
### Create the Potential solution variable
###
node_solution(device=device, region=region, name="Potential")

###
### Creates the Potential@n0 and Potential@n1 edge model
###
edge_from_node_model(device=device, region=region, node_model="Potential")

###
### Electric field on each edge, as well as its derivatives with respect to
### the potential at each node
###
edge_model(device=device, region=region, name="ElectricField",
           equation="(Potential@n0 - Potential@n1)*EdgeInverseLength")

edge_model(device=device, region=region, name="ElectricField:Potential@n0",
           equation="EdgeInverseLength")

edge_model(device=device, region=region, name="ElectricField:Potential@n1",
           equation="-EdgeInverseLength")

###
### Model the D Field
###
edge_model(device=device, region=region, name="DField",
           equation="Permittivity*ElectricField")

edge_model(device=device, region=region, name="DField:Potential@n0",
           equation="diff(Permittivity*ElectricField, Potential@n0)")

edge_model(device=device, region=region, name="DField:Potential@n1",
           equation="-DField:Potential@n0")

###
### Create the bulk equation
###
equation(device=device, region=region, name="PotentialEquation", variable_name="Potential",
         edge_model="DField", variable_update="default")


###
### Contact models and equations
###
for c in ("top", "bot"):
    contact_node_model(device=device, contact=c, name="%s_bc" % c,
                       equation="Potential - %s_bias" % c)

    contact_node_model(device=device, contact=c, name="%s_bc:Potential" % c,
                       equation="1")

    contact_equation(device=device, contact=c, name="PotentialEquation",
                     node_model="%s_bc" % c, edge_charge_model="DField")

###
### Set the contact 
###
set_parameter(device=device, name="top_bias", value=1.0e-0)
set_parameter(device=device, name="bot_bias", value=0.0)



edge_model(device=device, region="m1", name="ElectricField", equation="0")
edge_model(device=device, region="m2", name="ElectricField", equation="0")
node_model(device=device, region="m1", name="Potential", equation="bot_bias;")
node_model(device=device, region="m2", name="Potential", equation="top_bias;")


#solve -type dc -absolute_error 1.0 -relative_error 1e-10 -maximum_iterations 100 -solver_type iterative
solve(type="dc", absolute_error=1.0, relative_error=1e-10, maximum_iterations=30, solver_type="direct")

element_from_edge_model(edge_model="ElectricField", device=device, region=region)
print(get_contact_charge(device=device, contact="top", equation="PotentialEquation"))
print(get_contact_charge(device=device, contact="bot", equation="PotentialEquation"))

write_devices(file="cap2d.msh", type="devsim")
write_devices(file="cap2d.dat", type="tecplot")
write_devices(file="cap2d", type="vtk")