System equations coupling options
The SYSTEM line defines which partial differential equations (PDEs) are to be solved and how the equations are to be coupled in the nonlinear iteration.
CArriers = integer (default is 0) Electrons = logical Holes = logical N.temperature = logical P.temperature = logical
The above parameters define the PDEs to be solved. The Poisson equation is always solved, and optionally one can specify that continuity and/or energy balance PDEs be solved for the carriers (the corresponding PDE for carrier momentum always reduces to a closed form expression in the current version of PADRE and hence need not be explicitly selected). The continuity equations can be selected by setting CARRIERS to the number of carriers (0, 1 or 2) with the single carrier defined through the ELECTRONS and/or HOLES parameter; the default is ELECTRONS for CARRIERS=1. The parameters N.TEMPERATURE and P.TEMPERATURE select the equations for average electron and hole energy respectively.
coupling
NEwton = logical
or
Gummel = logical
or
COupling = integer vector
NEWTON specifies that all the equations be solved simulaneously in a single set of nonlinear iterations. GUMMEL forces each of the specified PDEs to be solved separately (e.g., plug-in iteration) so that in general there is an inner nonlinear iteration for each PDE and an outer iteration over all the equations. Alternatively, one can specify a general nonlinear construct (with arbitrary groupings of PDEs) using the COUPLING parameter. In this case the PDEs are selected using an integer code as follows:
1 Poisson equation 2 Electron continuity equation 3 Hole continuity equation 4 Electron energy balance equation 5 Hole energy balance equation
Groups of equations to be fully coupled are specified by concatenating digits, and individual groups of equations are separated by commas.
options
PRint = logical (default is false) Symmetric = logical (default is true) [Expert]
The PRINT parameter indicates that information about the memory allocated for the run should be printed to the PADRE standard output file. SYMMETRIC specifies that the symmetric block matrix data structure should be used wherever possible.
The following specifies a PDE system for a simulation with only holes and using the Gummel method:
SYSTEM GUMMEL CARR=1 HOLES
Solve the Poisson equation and the continuity and energy balance equations for electrons. Define an iteration strategy which couples the Poisson and continuity equations directly, but treats the energy balance equation separately.
SYSTEM ELECTRONS N.TEMP COUPLING=12,4