Parameters

Parameters can be set using the commands in Material Commands. There are two complementary formalisms for doing this.

Parameters

Parameters are set globally, on devices, or on regions of a device. The models on each device region are automatically updated whenever parameters change.

devsim.set_parameter(device="device", region="region",
  name="ThermalVoltage", value=0.0259)

They may also be used to control program behavior, as listed in Table 7:

Table 7 Parameters controlling program behavior.
Parameter Description
debug_level info, verbose python__verbosity
threads_available value=1, python__parallelization
threads_task_size value=?, python__parallelization
node_volume_model sec__cylindrical
edge_couple_model sec__cylindrical
edge_node0_volume_model sec__cylindrical
edge_node1_volume_model sec__cylindrical
element_edge_couple_model sec__cylindrical
element_node0_volume_model sec__cylindrical
element_node1_volume_model sec__cylindrical
extended_solver value=False Extended precision matrix and RHS assembly and error evaluations. Linear solver and circuit assembly is still double precision``
extended_model value=False Extended precision model evaluation
extended_equation value=False Extended precision equation evaluation

Material database entries

Alternatively, parameters may be set based on material types. A database file is used for getting values on the regions of the device.

devsim.create_db(filename="foodb")
devsim.add_db_entry(material="global", parameter="q", value=1.60217646e-19,
  unit="coul", description="Electron Charge")
devsim.add_db_entry(material="Si", parameter="one",
  value=1, unit="", description="")
devsim.close_db

When a database entry is not available for a specific material, the parameter will be looked up on the global material entry.

Discussion

Both parameters and material database entries may be used in model expressions. Parameters have precedence in this situation. If a parameter is not found, then DEVSIM will also look for a circuit node by the name used in the model expression.