Very simple semiconductor optical generation and recombination processes using FiPy

simple_semiconductor_rates.py

from fipy import *

#
#  Solution mesh
#
nx = 200
dx = 0.01
L = nx * dx
mesh = Grid1D(nx = nx, dx = dx)

#
#  Initial conditions
#
n0 = 1.

#
#  Boundary conditions
#
fluxLeft = 0.
valueRight = n0
bc1 = FixedFlux(faces=mesh.getFacesLeft(),  value=fluxLeft)
bc2 = FixedValue(faces=mesh.getFacesRight(), value=valueRight)
bcs = (bc1, bc2)

#
#  solution variable
#
n = CellVariable(name="n", mesh=mesh)
n.setValue(n0)

#
#  Diffusion term, with variable diffusion coefficient
#
D = 1.
diffusion = DiffusionTerm(coeff = D)


#
#  Source Term
#
B = 0.1
Io = 2.
ni = n0
alpha = 3
x = mesh.getCellCenters()[0]
from fipy.tools.numerix import exp
source = ImplicitSourceTerm(coeff=B*n) - B * ni**2 + Io * alpha * exp(-alpha * x)


#
#  Define equation
#
equation = diffusion + source
equation.solve(var=n, boundaryConditions=bcs)
viewer = Viewer( vars = (n,) )
viewer.plot()
raw_input("Press <return> to proceed...")

#
#  Solve using time-step
#
#timeStepDuration = 0.9 * dx**2 / (2 * D)
#steps = 1000
#for step in range(steps):
#    equation.solve(var=n, boundaryConditions=bcs, dt=timeStepDuration)
#    viewer = Viewer( vars = (n,) )
#    viewer.plot()
#    raw_input("Press <return> to proceed...")