DriftDiffusion2D

<electrical solver="DriftDiffusion2D">

Corresponding Python class: electrical.ddm2d.DriftDiffusion2D.

Finite element drift-diffusion electrical solver for 2D Cartesian geometry using finite-element method.

Attributes:
  • name (required) – Solver name.
Contents:
<geometry>

Geometry for use by this solver.

Attributes:
  • ref (required) – Name of a Cartesian2D geometry defined in the <geometry> section.
<mesh>

Rectangular2D mesh used by this solver.

Attributes:
  • ref (required) – Name of a Rectangular2D mesh defined in the <grids> section.
<voltage>

Voltage boundary conditions. See subsection Boundary conditions.

<loop>

Configuration of the self-consistent loop.

Attributes:
  • stat – Statistics assumed in drift-diffusion equations. (Maxwell-Boltzmann or Fermi-Dirac, default is Maxwell-Boltzmann)
  • conttype – Type of contacts. (ohmic or Schottky, default is ohmic)
  • SchottkyP – Schottky barrier for p-type contact. (float, default 0.0)
  • SchottkyN – Schottky barrier for n-type contact. (float, default 0.0)
  • Rsrh – Consider Shockley-Read-Hall recombination. (bool, default is no)
  • Rrad – Consider radiative recombination. (bool, default is no)
  • Raug – Consider Auger recombination. (bool, default is no)
  • Pol – Polarization effects. (bool, default is no)
  • FullIon – Complete ionization of dopants. (bool, default is yes)
  • maxerrVi – Limit for the initial potential estimate updates. (float (V), default 1e-06 V)
  • maxerrV0 – Limit for the built-in potential updates. (float (V), default 1e-06 V)
  • maxerrV – Limit for the potential updates. (float (V), default 1e-06 V)
  • maxerrFn – Limit for the electrons quasi-Fermi level updates. (float (eV), default 0.0001 eV)
  • maxerrFp – Limit for the holes quasi-Fermi level updates. (float (eV), default 0.0001 eV)
  • loopsVi – Loops limit for the initial potential estimate. (int, default 10000)
  • loopsV0 – Loops limit for the built-in potential. (int, default 200)
  • loopsV – Loops limit for the potential. (int, default 3)
  • loopsFn – Loops limit for the electrons quasi-Fermi level. (int, default 3)
  • loopsFp – Loops limit for the holes quasi-Fermi level. (int, default 3)
<matrix>

Matrix solver configuration.

Attributes:
  • algorithm – Algorithm used for solving set of linear positive-definite equations. (cholesky, gauss, or iterative, default is cholesky)
<iterative>

Parameters for iterative matrix solver. PLaSK uses NSPCG package for performing iterations. Please refer to its documentation for explanation of most of the settings.

Attributes:
  • maxit – Maximum number of iterations. (int, default 1000)
  • maxerr – Maximum iteration error. (float, default 1e-6)
  • noconv – Desired behavior if the iterative solver does not converge. (error, warning, or continue, default is warning)
  • accelerator – Accelerator used for iterative matrix solver. (cg, si, sor, srcg, srsi, basic, me, cgnr, lsqr, odir, omin, ores, iom, gmres, usymlq, usymqr, landir, lanmin, lanres, cgcr, or bcgs, default is cg)
  • preconditioner – Preconditioner used for iterative matrix solver. (rich, jac, ljac, ljacx, sor, ssor, ic, mic, lsp, neu, lsor, lssor, llsp, lneu, bic, bicx, mbic, or mbicx, default is ic)
  • nfact – This number initializes the frequency of partial factorizations. It specifies the number of linear system evaluations between factorizations. The default value is 1, which means that a factorization is performed at every iteration. (int, default 10)
  • ndeg – Degree of the polynomial to be used for the polynomial preconditioners. (int, default 1)
  • lvfill – Level of fill-in for incomplete Cholesky preconditioners. Increasing this value will result in more accurate factorizations at the expense of increased memory usage and factorization time. (int, default 0)
  • ltrunc – Truncation bandwidth to be used when approximating the inverses of matrices with dense banded matrices. An increase in this value means a more accurate factorization at the expense of increased storage. (int, default 0)
  • omega – Relaxation parameter. (float, default 1.0)
  • nsave – The number of old vectors to be saved for the truncated acceleration methods. (int, default 5)
  • nrestart – The number of iterations between restarts for the restarted acceleration methods. (int, default 100000)
Preconditioner choices:
rich Richardson’s method
jac Jacobi method
ljac Line Jacobi method
ljacx Line Jacobi method (approx. inverse)
sor Successive Overrelaxation
ssor Symmetric SOR (can be used only with SOR accelerator)
ic Incomplete Cholesky (default)
mic Modified Incomplete Cholesky
lsp Least Squares Polynomial
neu Neumann Polynomial
lsor Line SOR
lssor Line SSOR
llsp Line Least Squares Polynomial
lneu Line Neumann Polynomial
bic Block Incomplete Cholesky (ver. 1)
bicx Block Incomplete Cholesky (ver. 2)
mbic Modified Block Incomplete Cholesky (ver. 1)
mbicx Modified Block Incomplete Cholesky (ver. 2)
Accelerator choices:
cg Conjugate Gradient acceleration (default)
si Chebyshev acceleration or Semi-Iteration
sor Successive Overrelaxation (can use only SOR preconditioner)
srcg Symmetric Successive Overrelaxation Conjugate Gradient Algorithm (can use only SSOR preconditioner)
srsi Symmetric Successive Overrelaxation Semi-Iteration Algorithm (can use only SSOR preconditioner)
basic Basic Iterative Method
me Minimal Error Algorithm
cgnr Conjugate Gradient applied to the Normal Equations
lsqr Least Squares Algorithm
odir ORTHODIR, a truncated/restarted method useful for nonsymmetric systems of equations
omin ORTHOMIN, a common truncated/restarted method used for nonsymmetric systems
ores ORTHORES, another truncated/restarted method for nonsymmetric systems
iom Incomplete Orthogonalization Method
gmres Generalized Minimal Residual Method
usymlq Unsymmetric LQ
usymqr Unsymmetric QR
landir Lanczos/ORTHODIR
lanmin Lanczos/ORTHOMIN or Biconjugate Gradient Method
lanres Lanczos/ORTHORES or “two-sided” Lanczos Method
cgcr Constrained Generalized Conjugate Residual Method
bcgs Biconjugate Gradient Squared Method
<config>

Some important gain parameters.

Attributes:
  • strained – Boolean attribute indicating if the solver should consider strain in the active region. If set to yes then there must a layer with the role “substrate” in the geometry. The strain is computed by comparing the atomic lattice constants of the substrate and the quantum wells. (bool, default is no)
  • T0 – Reference temperature. This is the temperature used for initial computation of the energy levels. (float (K), default 300 K)