2. Release Notes

2.1. Introduction

DEVSIM download and installation instructions are located in Installation. The following sections list bug fixes and enhancements over time. Contact information is listed in Contact. A file named CHANGES.md is now distributed with DEVSIM, which can contain additional details concerning a new release.

2.2. Version 2.8.0

2.2.1. Python Scripts

Based on a contribution by [@simbilod](https://github.com/simbilod), all of the Python scripts have been reformatted. The build system was also updated to enforce Python script modifiecations are properly formatted when submitted to the project.

2.2.2. Data Output Reduction in Data file sizes

Based on a contribution by [@simbilod](https://github.com/simbilod) devsim.write_devices() now supports reducing the file size of data files by allowing users to specify a callback function to reduce data usage. In this example, only the NetDoping field is written to the Tecplot data file.

    include_test=lambda x: x in ("NetDoping",),
) FLOOPS Data File Output

The floops option for devsim.write_devices() has been removed.

2.2.3. Platform Support Windows Build Issue

During testing, it was found the Visual Studio 2022 builds were failing a test related to threading. This was found to be a problem with version 17.10, but not version 17.9. This affects the build automation, but should not affect the binary releases. Centos 7 End of Life

This is the last version to support Centos 7 before its end of life on June 30, 2024. After this date we will be moving to the AlmaLinux 8 based manylinux_2_28.

2.3. Version 2.7.3

Fixed issue [#133](https://github.com/devsim/devsim/issues/133) identified by [@yh-kwok](https://github.com/yh-kwok).

2.4. Version 2.7.2

  • macOS package is now Universal. Both x86_64 and arm64 will use clang compiler and macOS 12.0 is now the minimum supported version.

  • Update Boost version to 1.82

  • Improvements to extended precision complex numbers implementation to work with newer compilers.

  • Script to build for manylinux_2_28 (Centos 8)

  • Build Linux aarch64 from macOS system with docker

2.5. Version 2.7.1

  • Support for Linux aarch64, which can be run on Amazon AWS 64 bit instances.

  • Better implicit float conversions in parameters.

2.6. Version 2.7.0

2.6.1. Error Handling

More helpful exception information returned to Python if the error is considered fatal. This can be used to decide if the simulation can be restarted. Note that if this occurs during a solve, it is necessary for the user to restore the previous circuit and device solutions if a restart is desired. In addition, model evaluation is reset so that no false cyclic dependencies are reported after an error.

In this example code below, the previously DEVSIM FATAL error string will now provide the context that a floating point exception occurred and be handled in Python.

except error as msg:
    m = str(msg)
    if 'Convergence failure' in m:
    elif'floating point exception' in m:

2.7. Version 2.6.5

2.7.1. Bugs

Fixed issue [#123](https://github.com/devsim/devsim/issues/123) identified by [@gluek](https://github.com/gluek) This resulted in bad results on Windows and macOS in calculation of 3d mesh areas and volumes.

2.8. Version 2.6.4

2.8.1. SuperLU

Use MMD_ATA preconditioner for SuperLU builds.

2.8.2. Android

Android builds use special implementations for the Bernoulli function to prevent overflow.

2.8.3. Examples

testing/pythonmesh1d.py demonstrates how to get mesh information using devsim.get_element_node_list().

examples/diode/tran_diode.py demonstrates transient diode simulation.

2.9. Version 2.6.3

Allow Python threading during long solve operations.

2.10. Version 2.6.2

2.11. Version 2.6.1

2.11.1. Bugs

Fix issue [#116](https://github.com/devsim/devsim/issues/116) where the contact current was being calculated incorrectly in transient mode.

2.12. Version 2.6.0

2.12.1. Symbolic Factorization Reuse

The Intel MKL solver will now use reuse the symbolic factorization, if the simulation matrix sparse matrix pattern has not changed after the second nonlinear solver iteration. This reduces simulation time, but can result in numerical differences in the simulation result. Setting the environment variable, DEVSIM_NEW_SYMBOLIC, will do a new symbolic factorization for each iteration.

This behavior may be controlled by using this option in the devsim.solve() command

solve(symbolic_iteration_limit = -1)

where setting the value to -1 will create a new symbolic factorization for all nonlinear iterations. Setting the value to a number greater than 0 will mark all iterations afterwards for reusing the previous symbolic factorization.

2.12.2. Reset Simulator

The devsim.reset_devsim() command will clear all simulator data, so that a program restart is not necessary.

2.12.3. Build Infrastructure LAPACK is Optional

When LAPACK functions are not available, it is now possible to use Eigen instead. BLAS is still required. It is up to the direct solver being used to determine necessary LAPACK functions. Self Contained Build

The build infrastructure is being updated to support a small application build on different systems. SuperLU Solver

For self contained builds, some commands are removed and SuperLU is the only available solver.

2.12.4. Citing DEVSIM

CITATION.md has been updated with recent articles written about the simulator.

2.12.5. Documentation

Fix documentation issue in 1D diode where the length of the 1D diode was incorrect.

Fix issue where surface_area_model was missing from Parameters controlling program behavior..

Added table of environment variables controlling program behavior in Environment controlling program behavior..

2.13. Version 2.5.0

UMFPACK 5.1 is the new default when the Intel MKL is not available, making this the default for the macOS arm64 platform.

SuperLU is removed and no longer available as a solver.

Regression scripts were passing when there were numerical differences in the data diff comparison. This is now corrected and the regression results have been updated on all platforms.

For those building the software, the EXPLICIT_MATH_LOAD CMAKE option has been removed, so that the software is not directly linked to any math library.

The license text for the Apache 2.0 license has been replaced with the SPDX format of the license string. This ensures that the text can be used in a consistent manner across all source files.

2.14. Version 2.4.0

2.14.1. Determine Loaded Math Libraries

To determine the loaded math libraries, use


2.14.2. UMFPACK 5.1 Solver

The UMFPACK 5.1 solver is now available as a shared library distributed with the software. It is licensed under the terms of the LGPL 2.1 and our version is hosted here:


Please note that this version uses a scheme to provide the needed math library functions when the library is loaded.

In order to use this library, a shim script is provided to load UMFPACK and set it as the solver. Please see this example:

python -mdevsim.umfpack.umfshim ssac_cap.py

2.14.3. Direct Solver Callback

It is now possible to setup call a custom direct solver. The direct solver is called from Python and the callback is implemented by setting these parameters:

devsim.set_parameter(name="direct_solver", value="custom")
devsim.set_parameter(name="solver_callback", value=local_solver_callback)

Where the first parameter enables the use of the second parameter to set a callback function. Please see the testing/umfpack_shim.py for a sample implementation using UMFPACK 5.1.

2.14.4. Apple M1

On this platform, the software does not check for floating point exceptions (FPEs) during usage of the direct solver. During testing, it was discovered that FPEs were occuring during factorization for both the SuperLU and the UMFPACK. Removing this check allows more of the tests to run through to completion.

2.14.5. Bugs

Fix issue [#104](https://github.com/devsim/devsim/issues/104) where the 2D MOSFET example was not fully connected across region interfaces.


This was resulting in an FPE during testing on macOS M1.

2.15. Version 2.3.8

2.15.1. Bugs

[@ryan3141](https://github.com/ryan3141) fixed an issue where math functions added with devsim.register_function() were not available in extended precision model evaluation. The testing/testfunc_extended.py test is added to validate the fix.

Update NOTICE with the license files from the various dependencies.

2.16. Version 2.3.7

2.16.1. Apple M1 Support

Intel MKL Pardiso not available, so using system BLAS/LAPACK or openblas by default. In addition, SuperLU, is used instead of the MKL Pardiso. This results in some test failures, based on the use of a different solver, and not the OS architecture.

Extended precision is enabled.

Enabled by running pip install.

The regression results are in this newly created repo:

2.16.2. Python Notebook Example With 3D Visualization

A plotting example using pyvista is presented in examples/plotting/visualization.ipynb. This example was provided by [@simbilod](https://github.com/simbilod).

2.16.3. Bugs

When instantiating a mesh from Gmsh, contact and interface related errors to dimensionality have an improved error message.

2.17. Version 2.3.6

On Windows the DEVSIM_MATH_LIBS now uses the ; as the path separator, while macOS and Linux still use :.

The math library search order is then:

  • The math libraries listed in the DEVSIM_MATH_LIBS environment variable, with the appropriate separator.

  • The Intel Math Kernel Library

  • These dynamic libraries * OpenBLAS (e.g. libopenblas.so) * LAPACK (e.g. liblapack.so) * BLAS (e.g. libblas.so)

All platforms will search for the Intel MKL by trying several version numbers. When the Intel MKL is not available, the direct solver will switch from Intel MKL Pardiso to SuperLU.

On macOS and Linux, the RPATH has been modified to look in places relative to the devsim module, instead of using CONDA_PREFIX or VIRTUAL_ENV.

  • macOS : @loader_path;@loader_path/../lib;@loader_path/../../../../lib;@executable_path/../lib

  • Linux : $ORIGIN:$ORIGIN/../lib:$ORIGIN/../../../../lib

2.18. Release 2.3.1

2.18.1. Python PIP Package

DEVSIM is now available via pip for macOS, Linux, and Microsoft Windows. To install this package for your platform:

pip install devsim

Please see the INSTALL.md file in the distribution for more information. These files may be found in the $CONDA_PREFIX/devsim_data directory of your Anaconda environment. If you are using venv, it may be found in the $VIRTUAL_ENV/devsim_data of your virtual environment.

2.18.2. Remove Windows MSYS Build

The msys build is removed as an available binary package. Windows is still supported through the use of the Visual C++ compiler build.

2.18.3. Build Notes

The compiler for the Linux build are now upgraded to devtoolset-10 and is now built on manylinux2014.

Boost is now added as a submodule, instead of using system libraries or Anaconda Python versions. The Linux build no longer requires Anaconda Python.

2.19. Release 2.2.0

2.19.1. Device and mesh deletion commands

The devsim.delete_device() command makes it possible to delete devices so they will no longer be solved in the simulation. Any parameters set on the device are also removed from the system.

The devsim.delete_mesh() command makes it possible to delete meshes. Once a mesh has been deleted, it is no longer possible to create devices from it using the devsim.create_device() command.

2.19.2. Extended Precision

Extended precision is now available on Windows builds using the Visual Studio Compiler. Note that this precision is not as accurate as the float128 type used on other systems.

2.19.3. Direct Solver

SuperLU has been updated from version 4.3 to version 5.3. It is the solver used when the Intel MKL is not available.

2.19.4. Code Quality

Fixed defects found in Coverity scanning.

2.20. Release 2.1.0

2.20.1. Explicit math library loading

Since the Intel Math Kernel Library started versioning the names of their dynamic link libraries, it has been difficult to maintain a proper Anaconda Python environment when the version has been updated. With this release, it is possible to use any recent version of the Intel MKL. In addition, the user is able to load alternative BLAS/LAPACK math libraries. Intel MKL

From DEVSIM Version 2.1.0 onward, a specific version is not required when loading the Intel MKL. If the Intel MKL is not found, the import of the devsim module will fail, and an error message will be printed. This method is the default, and should work when using an Anaconda Python environment with the mkl package installed.

When using a different Python distribution, or having an installation in a different place, it is possible to specify the location by modifying the LD_LIBRARY_PATH environment variable on Linux, or using DYLD_LIBRARY_PATH on Apple macOS. The explicit path may be set to the MKL math libraries may be set using the method in the next section. Loading other math libraries

It is possible to load alternative implementations of the BLAS/LAPACK used by the software. The DEVSIM_MATH_LIBS environment variable may be used to set a : separated list of libraries. These names may be based on relative or absolute paths. The program will load the libraries in order, and stop when all of the necessary math symbols are supplied. If symbols for the Intel MKL are detected, then the Pardiso direct solver will be enabled.

Linux example:

export DEVSIM_MATH_LIBS=libblas.so:liblapack.so

Apple macOS example:

export DEVSIM_MATH_LIBS=libblas.dylib:liblapack.dylib

2.20.2. Direct solver selection

The direct solver may be selected by using the direct_solver parameter.

devsim.set_parameter(name='direct_solver', value='mkl_pardiso')

The following options are available:

  • mkl_pardiso Intel MKL Pardiso

  • superlu SuperLU 4.3

The default is mkl_pardiso when the Intel MKL is loaded. Otherwise, the default will switch to superlu.

2.20.3. Kahan summation in extended precision mode

The kahan3 and kahan4 functions are now using the Kahan summation algorithm for extended precision model evaluation. Previously, this algorithm was replaced with 128-bit floating point addition and subtraction in releases that support extended precision mode. With this change, better than 128-bit floating precision is available when extended precision is enabled.

devsim.set_parameter(name = "extended_model", value=True)

The testing/kahan_float128.py test has been added.

2.20.4. Visual Studio 2022

The Microsoft Windows win64 release version is now built using the Visual Studio 2022 compiler. For users needing extended precision on the Windows platform, the msys build is recommended.

2.21. Release 2.0.1

2.21.1. Update documentation files

The following files were updated in the text documentation distributed with the software.


  • INSTALL.md

  • README.md

This was done to create a version to coincide with this paper in the Journal of Open Source Software.

Sanchez, J. E., (2022). DEVSIM: A TCAD Semiconductor Device Simulator. Journal of Open Source Software, 7(70), 3898, https://doi.org/10.21105/joss.03898.

2.21.2. Update MKL Version

The release version of this software is build against version 2 of the Intel MKL, which corresponds to the latest version of Anaconda Python.

2.22. Release 2.0.0

2.22.1. New Major Version

Based on the change in the sections Contact and Interface Equation Commands and Transient Simulation. The major version of the software has been updated to 2. Existing scripts may need to be updated for this change.

2.22.2. Contact and Interface Equation Commands

The previously deprecated variable_name option is no longer accepted by the devsim.contact_equation() and devsim.interface_equation() commands. This has been updated in the documentation.

2.22.3. Documentation Manual Documentation Files

Some out of date files (e.g. RELEASE, INSTALL, …) have been removed. The README.md has been updated and the INSTALL.md has been added.

2.22.4. Python Packages

The rampbias function in the devsim.python_packages.ramp module has been fixed to properly reduce the bias when there is a convergence failure.

Python 2.7 specific instructions in User Interface has been removed.

2.22.5. Solver Transient Simulation

  • Fixed bug with transient_tr (trapezoidal) time integration method in the devsim.solve() command where the wrong sign was used to integrate previous time steps.

  • Fixed bug in the charge error calculation, which calculates the simulation result with that a forward difference projection.

  • Added testing/transient_rc.py test which compares simulation with analytic result for RC circuit.

  • Added devsim.set_initial_condition() to set initial transient condition as alternative to using the transient_dc option to the devsim.solve() command. Suitable options for this command may be provided from the get_matrix_and_rhs() command. Convergence Tests

The maximum_error and maximum_divergence options where added to the devsim.solve() command. If the absolute error of any iteration goes above maximum_error, the simulation stops with a convergence failure. The maximum_divergence is the maximum number of iterations that the simulator error may increase before stopping. Verbosity

During the devsim.solve(), circuit node and circuit solution information is no longer printed to the screen for the default verbosity level. In addition, the number of equations per device and region is no longer displayed at the start of the first iteration. Intel Math Kernel Library

The Intel Math Kernel Library now uses versioned library names. Binary releases are now updated against the latest versioned dll names from MKL available in the Anaconda Python distribution. SuperLU

The code now supports newer versions of SuperLU. The release version is still using SuperLU 4.3 for the iterative solution method, and the Intel MKL Pardiso for the direct solve method. Simulation Matrix

The devsim.get_matrix_and_rhs() command was not properly accepting the format parameter, and was always returning the same type.

2.22.6. Add Interface supporting Periodic Boundary Conditions

The devsim.create_interface_from_nodes() command makes it possible to create an interface with non coincident nodes. This enables the use of periodic boundary conditions.

2.22.7. Build Scripts

The build scripts have been updated on all platforms to be less dependent on specific Python 3 versions.

An updated Fedora build script has been added. It uses the system installed SuperLU as the direct solver.

2.23. Release 1.6.0

2.23.1. Array Type Input and Output

In most circumstances, the software now returns numerical data using the Python array class. This is more efficient than using standard lists, as it encapsulates a contiguous block of memory. More information about this class can be found at https://docs.python.org/3/library/array.html. The representation can be easily converted to lists and numpy arrays for efficient manipulation.

When accepting user input involving lists of homogenous data, such as devsim.set_node_values() the user may enter data using either a list, string of bytes, or the array class. It may also be used to input numpy arrays or any other class with a tobytes method.

2.23.2. Get Matrix and RHS for External Use

The devsim.get_matrix_and_rhs() command has been added to assemble the static and dynamic matrices, as well as their right hand sides, based on the current state of the device being simulated. The format option is used to specify the sparse matrix format, which may be either in the compressed column or compressed row formats, csc or csr.

2.23.3. Maximum Divergence Count

If the Newton iteration errors keep increasing for 20 iterations in a row, then the simulator stops. This limit was previously 5. This gives a chance for a solution to be found, when there is a poor initial guess.

2.23.4. Mesh Visualization Element Orientation

Elements written to the tecplot format in 2d and 3d have node orderings compatible with the element connectivity in visualization formats. Specifying the reorder=True option in devsim.get_element_node_list() will result in node ordering compatible with meshing and visualization software.

2.23.5. Figure annotation

Fig. 4.2 has been updated, showing the EdgeNodeVolume.

2.23.6. Citation

The Citing this Work section has been added with information on how to cite the manual and the simulator.

2.23.7. Documentation License

The license terms have been changed in Documentation License so that derivative works are allowed.

2.23.8. Online Forum

The online forum for discussion about the software has moved to https://forum.devsim.org. This has been updated in Contact.

2.24. Release 1.5.1

2.24.1. Installation Script

A new installation script is in the base directory of the package. It provides instructions of completing the installation to the python environment without having to set the PYTHONPATH environment variable. It notifies the user of missing components to finish the installation within an Anaconda or Miniconda environment.

To use the script, use the following command inside of the devsim directory.

python install.py

The install script will write a file named lib/setup.py, which can be used to complete the installation using pip. The script provides instructions for the installation and deinstallation of devsim.

INFO: Writing setup.py
INFO: Please type the following command to install devsim:
INFO: pip install -e lib
INFO: To remove the file, type:
INFO: pip uninstall devsim

2.24.2. Math Functions Table

The list of available math functions, Table 10.2, has been reformatted, and parts have been split into the tables referenced in the next few sections.

2.24.3. Error Functions

The following inverse functions and their derivatives are now available in the model interpreter, and also listed in Table 10.3.

  • erf_inv Inverse Error Function

  • erfc_inv Inverse Complimentary Error Function

  • derf_invdx Derivative of Inverse Error Function

  • derfc_invdx Derivative of Complimentary Inverse Error Function

2.24.4. Fermi Integral

The Joyce-Dixon approximation [4] for the Fermi integral and its inverse are now calculated with extended floating point precision, when extended precision is enabled. These functions are now listed in Table 10.4.

  • Fermi Fermi integral

  • dFermidx Derivative of Fermi integral

  • InvFermi Inverse Fermi integral

  • dInvFermidx Derivative of inverse Fermi Integral

The following examples are available:

  • testing/Fermi1.py Fermi integral

  • testing/Fermi1_float128.py Fermi integral in extended floating point precision

2.24.5. Gauss-Fermi Integral

The Gauss-Fermi Integral, using Paasch’s equations [7] are now available, and are listed in Table 10.5..

  • gfi Gauss-Fermi Integral

  • dgfidx Derivative of Gauss-Fermi Integral

  • igfi Inverse Gauss-Fermi Integral

  • digfidx Derivative of Inverse Gauss-Fermi Integral

Each of these functions take two arguments, zeta and s. The derivatives with respect to the first argument are provided.

The following examples are available:

  • testing/GaussFermi.py Gauss-Fermi integral

  • testing/GaussFermi.py Gauss-Fermi integral with extended floating point precision

2.25. Release 1.5.0

The devsim.custom_equation() command has been modified to require a third return value. This boolean value denotes whether the matrix entries should be row permutated or not. For the bulk equations this value should be True. For interface and contact boundary conditions, this value should be False. More information is available in Custom Matrix assembly.

It is now possible to replace an existing custom_equation.

The file examples/diode/diode_1d_custom.py demonstrates custom matrix assembly and can be directly compared to examples/diode/diode_1d.py.

The EdgeNodeVolume model is now available for the volume contained by an edge and is referenced in Edge models.

The devsim.equation() command has removed support for the volume_model option. It has been replaced with:

  • volume_node0_model

  • volume_node1_model

This makes it possible to better integrate nodal quantities on the volumes of element edges. For example, a field dependent generation-recombination rate can be volume integrated separately for each node of an element edge.

The devsim.contact_equation() now supports the following options:

  • edge_volume_model

  • volume_node0_model

  • volume_node1_model

This makes it possible to integrate edge and element edge quantities with respect to the volume on nodes of the edge at the contact. This is similar to devsim.equation(), described in June 7, 2015.

The integration parameters for edge_volume_model are set with

  • edge_node0_volume_model (default EdgeNodeVolume Edge models )

  • edge_node1_volume_model (default EdgeNodeVolume)

and for volume_model with:

These parameters are applicable to both devsim.equation() devsim.contact_equation().

2.26. Release 1.4.14

2.26.1. Platforms

Windows 32 bit is no longer supported. Binary releases of the Visual Studio 2019 MSYS2/Mingw-w64 64-bit builds are still available online for Microsoft Windows 10.

On Linux, the releases are now on Centos 7, as Centos 6 has reached its end of life on November 30, 2020.

Please see Supported platforms for more information.

For future development, C++17 is now the recommended C++ compiler standard.

2.27. Release 1.4.13

The node indexes with the maximum error for each equation will be printed when debug_level is verbose.

devsim.set_parameter(name="debug_level", value="verbose")

These are printed as RelErrorNode and AbsErrorNode:

Region: "gate"      RelError: 5.21531e-14   AbsError: 4.91520e+04
  Equation: "ElectronContinuityEquation"    RelError: 4.91520e-16   AbsError: 4.91520e+04
    RelErrorNode: 129       AbsErrorNode: 129

This information is also returned when using the info=True option on the devsim.solve() command for each equation on each region of a device.

If the info flag is set to True on the solve command, the iteration information will be returned, and an exception for convergence will no longer be thrown. It is the responsibility of the caller to test the result of the solve command to see if the simulation converged. Other types of exceptions, such as floating point errors, will still result in a Python exception that needs to be caught.

2.28. Release 1.4.12

Element assembly for calculation of current and charges from the device into the circuit equation are fixed. These tests are added:

  • testing/cap_2d_edge.py

  • testing/cap_2d_element.py

  • testing/cap_3d_edge.py

  • testing/cap_3d_element.py

The edge variant is using standard edge based assembly, and the element variant is using element-based assembly.

2.29. Release 1.4.11

The devsim.element_pair_from_edge_model() command is available to calculate element edge components averaged onto each node of the element edge. This makes it possible to create an edge weighting scheme different from those used in devsim.element_from_edge_model(). The examples examples/diode/laux2d.py (2D) and examples/diode/laux3d.py (3D) compare the built-in implementations of these commands with equivalent implementations written in Python

Fixed issue where command option names where not always shown in the documentation.

The platform specific notes now clarify that any version of Python 3 (3.6 or higher) is supported.

  • linux.txt

  • windows.txt

  • macos.txt

2.30. Release 1.4.10

Fixed crash when evaluating element edge model in 3D.

Fixed potential error using devsim.delete_node_model() and similar deletion commands.

2.31. Release 1.4.9

Support for loading mesh files containing element edge data.

2.32. Release 1.4.8

In transient mode, the convergence test was flawed so that the charge_error was the only convergence check required for convergence. The software now ensures all convergence criteria are met.

2.33. Release 1.4.7

2.33.1. Models

In the simple physics models, the sign for time-derivative terms was wrong for the electron and hole continuity equations. This affects small-signal and noise simulations. The example at examples/diode/ssac_diode.py was updated to reflect the change.

2.33.2. Platforms

Fix build script issue for Apple macOS on Travis CI, updated the compiler to g++-9.

Update Centos 6 build from devtoolset-6 to devtoolset-8.

2.34. Release 1.4.6

2.34.1. Version Information

Parameter info can be queried for getting version information. The file testing/info.py contains an example.

python info.py
{'copyright': 'Copyright © 2009-2020 DEVSIM LLC', 'direct_solver': 'mkl_pardiso', 'extended_precision': True, 'license': 'Apache License, Version 2.0', 'version': '1.4.6', 'website': 'https://devsim.org'}

2.34.2. Extended Precision

The example examples/diode/gmsh_diode3d_float128.py provides an example where extended precision is enabled.

2.34.3. Python Formatting

The Python scripts in the examples and testing directories have been reformatted to be more consistent with language standards.

2.34.4. Platforms

Microsoft Windows 10 is supported and is now compiled using Microsoft Visual Studio 2019.

Microsoft Windows 7 is no longer supported, as Microsoft has dropped support as of January 14, 2020.

2.34.5. External Meshing

Support for reading meshes from Genius Device Simulator has been completely removed from DEVSIM.

2.35. Release 1.4.5

An MSYS2/Mingw-w64 build is available for 64-bit Microsoft Windows. This build, labeled devsim_msys_v1.4.5, enables the use of the 128-bit floating point precision already available on the Apple macOS and Linux platforms.

2.36. Release 1.4.4

2.36.1. Bug Fixes

An intermittent crash on Microsoft Windows 10 was occuring at the end of the program. It is now fixed.

2.36.2. Documentation

A file named CHANGES.md is now distributed with DEVSIM, detailing changes to the program.

2.36.3. Internal changes

  • Regression system script refactored to Python

  • Refactored threading code using C++11 function

  • Refactored timing functions for verbose mode using C++11 functions

  • Refactored FPE detection code to C++11 standard

2.37. Release 1.4.3

Fix failures with the following commands:

2.38. Release 1.4.2

In this release there are the following improvements.

  • Errors due to floating point exceptions and failed matrix factorization are not fatal.

  • The Apple macOS release fixes runtime issues with macOS 10.13 (High Sierra).

  • The provided binary releases utilize more libraries from Anaconda.

2.39. Release 1.4.1

2.39.1. Math Functions

The cosh, sinh, tanh, are now available math functions. Please see Table 10.2. In addition, all of the functions in the table, except for Fermi and inverse Fermi functions, are evaluate in extended precision mode. This mode may be enabled using the parameters discussed in Extended Precision.

2.39.2. Element Model Memory Leak

A large memory leak was occurring during the evaluation of element edge models created with devsim.element_from_edge_model(). It is now fixed and memory usage is now stable when these models are evaluated.

2.39.3. Python 3 API Memory Leak

A small memory leak could occur when devsim functions where called, or when data was returned. These reference counting issues are now fixed.

2.40. Release 1.4.0

The devsim.custom_equation() and devsim.register_function() commands take Python functions, instead of the a string with the function name.

The following commands are available to store data on edges and element edges:

2.41. Release 1.3.0

2.41.1. Python 3 Examples

All of the Tcl regression tests in the testing directory have been converted to Python 3. These tests serve as examples for features that were previously only tested using Tcl scripting.

2.41.2. Tcl Support Deprecated

Tcl support is deprecated and will be removed in a future release of the software.

2.41.3. Binary Releases Scripting Languages

Python 3 is now the only scripting language in the releases available from:

https://github.com/devsim/devsim/releases Math Library

The Microsoft Windows version now uses Intel MKL Pardiso for direct matrix factorization. Both Linux and Apple macOS have been using Intel MKL Pardiso since November 1, 2015. Binary releases for all operating systems use BLAS/LAPACK routines from Intel Math Kernel Library.

2.42. Release 1.2.0

DEVSIM releases have better support for Python 3. Using the stable ABI, the software is able to run newer Python 3 releases, without rebuilding the software.

Support for Python 2.7 has been removed.

The banner has been removed when the DEVSIM module is imported.

The symdiff python module is now part of the DEVSIM release. This module has additional features not available using the devsim.symdiff() command from DEVSIM. By first setting the PYTHONPATH variable to the lib directory in the DEVSIM distribution, symdiff is loaded by using

import symdiff

Documentation is available in the doc directory of this distribution. Examples are available in the examples/symdiff directory.

2.43. Release 1.1.0

The Bernoulli function, \(B(x)\),

\[B \left( x \right) = \frac{x}{\mathrm{e}^x - 1}\]

and its derivative,

\[dBdx \left( x \right) = \frac{\mathrm{e}^x - 1 - x \mathrm{e}^x}{\left(\mathrm{e}^x - 1\right)^2}\]

have been refactored. They are used to calculate electron and hole current densities using the Scharfetter-Gummel method [10].

The Bernoulli function has numerical issues when \(x\) approaches 0 and requires special evaluation. In this release, DEVSIM, takes advantage of C++11 math library functions for evaluating the denominator.

In addition, these functions are evaluated with extended precision, when this mode is enabled in the simulator. This mode is described in Extended Precision and controlling parameters are in Parameters controlling program behavior..

Users should expect that simulation results should change in the number of solver iterations and small differences in simulation results. This and other functions are listed in Predefined Functions.

2.44. Release 1.0.0

2.44.1. Documentation

The formatting of the PDF and online documentation has been improved. Also significant changes have been made to the way DEVSIM is called from Python.

2.44.2. Version

Due to the numerous changes in the Python API, the version number has been updated to having a major revision of 1. We adopt the semantic version numbering presented at https://semver.org. The version number can be accessed through the Python interface using the devsim.__version__ variable.

2.44.3. Operating Systems

The Microsoft Windows 32-bit operating system is now supported in addition to the platforms listed in Supported platforms.

2.44.4. Python Support

DEVSIM is now loaded as a shared library from any compatible Python interpreter. Previously, DEVSIM binaries contained an embedded Python interpreter. The following versions of Python are supported in this release

  • 2.7

  • 3.6

  • 3.7

By first setting the PYTHONPATH variable to the lib directory in the DEVSIM distribution, devsim is loaded by using

import devsim

from Python. Previous releases of devsim used the ds module, the manual will be updated to reflect the change in module name.

Many of the examples in the distribution rely on the python_packages module, which is available by using:

import devsim.python_packages

The default version of Python for use in scripts is Python 3.7. Scripts written for earlier versions of Python 3 should work. Python 2.7 is deprecated for future development.

Anaconda Python 3.7 is the recommended distribution and is available from https://continuum.io. The Intel Math Kernel Library is required for the official DEVSIM releases. These may be installed in Anaconda using the following command:

conda install mkl

On the Microsoft Windows platform, the following packages should also be installed:

conda install sqlite zlib

Some of the examples and tests also use numpy, which is available using:

conda install numpy

Please see User Interface and Installation for more information.

2.44.5. GMSH Support

Gmsh has announced a new version of their mesh format 4.0. DEVSIM currently supports the previous version, 2.2. To load a file from Gmsh, it is now necessary to either:

A future release of DEVSIM will provide this capability.

2.44.6. CGNS Support

Support for loading CGNS files is deprecated, and is no longer part of the official releases. Please see Using an external mesher for more information about importing meshes from other tools.

2.45. July 20, 2018

2.45.1. Documentation

The documentation has a new license, which is described in Copyright. The source files are now available for download from: https://github.com/devsim/devsim_documentation.

2.45.2. Python 3 Support

Python 3 executable, devsim_py3 is now supplied in addition to standard Python 2 executable, devsim.

2.45.3. Element Information

The devsim.get_element_node_list() retrieves a list of nodes for every element on a region, contact, or interface.

2.45.4. Interface Boundary Condition

The type=hybrid option is now available for the devsim.interface_equation() command. Please see Interface equation assembly for information about boundary conditions.

2.45.5. Interace Equation Coupling

The name0, and name1 options are now available for the devsim.interface_equation() command. They make it possible to couple dissimilar equation names across regions.

2.45.6. Interface and Contact Surface Area

Contact surface area is no longer included in SurfaceArea node model. It is now placed in ContactSurfaceArea. These are listed in Table 4.1.

2.45.7. Bug Fixes

2.45.8. Extended Precision

The following new parameters are available:

  • extended_solver, extended precision matrix for Newton and linear solver

  • extended_model, extended precision model evaluation

  • extended_equation, extended precision equation assembly

When compiled with 128-bit extended precision support, these options enable calculations to be performed with higher precision. Default geometric models, are also calculated with extended precision.

devsim.set_parameter(name = "extended_solver", value=True)
devsim.set_parameter(name = "extended_model", value=True)
devsim.set_parameter(name = "extended_equation", value=True)

Currently, the Linux and gcc-based Apple macOS versions have extended precision support.

2.46. May 15, 2017

2.46.1. Platforms

  • The Ubuntu 16.04 (LTS) platform is now supported.

  • The Ubuntu 12.04 (LTS), Centos 5 (Red Hat 5 compatible) platforms are no longer supported. These platforms are no longer supported by their vendors.

  • Apple macOS compiled with flat_namespace to allow substitution of dynamically linked libraries.

  • Microsoft Windows 7 is compiled using Microsoft Visual Studio 2017.

2.46.2. Binary Releases

  • Releases available from https://github.com/devsim/devsim/releases.

  • Centos 6 released is linked against the Intel Math Kernel Library.

  • Microsoft Windows 7 release is linked against the Intel Math Kernel Library

  • Apple macOS can optionally use the Intel Math Kernel Library.

  • Anaconda Python 2.7 is the recommended distribution.

  • Please see release notes for more information.

2.46.3. Bug Fixes

  • 3D element edge derivatives were not being evaluated correctly

  • 3D equation model evaluation for element edge models

2.46.4. Enhancements

  • Build scripts are provided to build on various platforms.

  • DEVSIM mesh format stores elements, instead of just nodes, for contact and interfaces

  • The devsim.create_gmsh_mesh() command can be used to create a device from a provided list of elements.

2.46.5. Example Availability

2.47. February 6, 2016

DEVSIM is now covered by the Apache License, Version 2.0 [11]. Please see the NOTICE and LICENSE file for more information.

2.48. November 24, 2015

2.48.1. Python Help

The Python interpreter now has documentation for each command, derived from the documentation in the manual. For example, help for the devsim.solve() can be found using:


2.48.2. Manual Updates

The manual has been updated so that commands are easier to find in the index. Every command now has a short description. Cross references have been fixed. The date has been added to the front page.

2.49. November 1, 2015

2.49.1. Convergence Info

The devsim.solve() now supports the info option. The solve command will then return convergence information.

2.49.2. Python Interpreter Changes

The way DEVSIM commands are loaded into the devsim module has been changed. It is now possible to see the full list of DEVSIM commands by typing


in the Python interpreter.

2.49.3. Platform Improvements and Binary Availability

Many improvements have been made in the way binaries are generated for the Linux, Apple macOS, and Microsoft Windows platforms.

For Linux (see linux.txt):

  • Create Centos 5, (Red Hat Enterprise Linux 5 compatible) build

  • Build uses Intel Math Kernel Library math libraries (community edition)

  • Build uses any compatible Python 2.7, including Anaconda

  • Build compatible with newer Linux distributions.

For Apple macOS (see macos.txt):

  • Uses the system Python 2.7 on macOS 10.10 (Yosemite)

  • Provide instructions to use Anaconda Python

For Microsoft Windows (see windows.txt):

  • Uses any compatible Python 2.7, including Anaconda

  • Build uses Intel Math Kernel Library Community Edition

Binary releases are available for these platforms at https://devsim.org.

2.50. September 6, 2015

The devsim.set_node_values() takes a new option, values. It is a list containing values to set for all of the nodes in a region.

The following new commands have been added:

2.51. August 10, 2015

The devsim.create_contact_from_interface() may be used to create a contact at the location of an interface. This is useful when contact boundary conditions are needed for a region connected to the interface.

2.52. July 16, 2015

The devsim.set_node_value() was not properly setting the value. This issue is now resolved.

2.53. June 7, 2015

The devsim.equation() now suppports the edge_volume_model. This makes it possible to integrate edge quantities properly so that it is integrated with respect to the volume on nodes of the edge. To set the node volumes for integration, it is necessary to define a model for the node volumes on both nodes of the edge. For example:

devsim.edge_model(device="device", region="region", name="EdgeNodeVolume",
set_parameter(name="edge_node0_volume_model", value="EdgeNodeVolume")
set_parameter(name="edge_node1_volume_model", value="EdgeNodeVolume")

For the cylindrical coordinate system in 2D, please see Cylindrical Coordinate Systems.

macOS 10.10 (Yosemite) is now supported. Regression results in the source distribution are for a 2014 Macbook Pro i7 running this operating system.

2.54. October 4, 2014

2.54.1. Platform Availability

The software is now supported on the Microsoft Windows. Please see Supported platforms for more information.

2.55. December 25, 2013

2.55.1. Binary Availability

Binary versions of the DEVSIM software are available for download from http://sourceforge.net/projects/devsim. Current versions available are for

  • macOS 10.10 (Yosemite)

  • Red Hat Enterprise Linux 6

  • Ubuntu 12.04 (LTS)

Please see Installation for more information.

2.55.2. Platforms

macOS 10.10 (Yosemite) is now supported. Support for 32 bit is no longer supported on this platform, since the operating system is only released as 64 bit.

Regression data will no longer be maintained in the source code repository for 32 bit versions of Ubuntu 12.04 (LTS) and Red Hat Enterprise Linux 6. Building and running on these platforms will still be supported.

2.55.3. Source code improvements

The source code has been improved to compile on macOS 10.10 (Yosemite) and to comply with C++11 language standards. Some of the structure of the project has been reorganized. These changes to the infrastructure will help to keep the program maintainable and useable into the future.

2.56. September 8, 2013

2.56.1. Convergence

If the simulation is diverging for 5 or more iterations, the simulation stops.

2.56.2. Bernoulli Function Derivative Evaluation

The dBdx math function has been improved to reduce overflow.

2.56.3. Default Edge Model

The edge_index is now a default edge models created on a region Table 4.2.

2.57. August 14, 2013

2.57.1. SYMDIFF functions

The vec_max and vec_min functions have been added to the SYMDIFF parser (Table 10.2). The vec_sum function replaces sum.

2.57.2. Default Node Models

The coordinate_index and node_index are now part of the default node models created on a region (Table 4.1}).

2.57.3. Set Node Value

It is now possible to use the devsim.set_node_value() to set a uniform value or indexed value on a node model.

2.57.4. Fix Edge Average Model

Fixed issue with devsim.edge_average_model() during serialization to the DEVSIM format.

2.58. July 29, 2013

2.58.1. DEVSIM is open source

DEVSIM is now an open source project and is available from https://github.com/devsim/devsim. License information may be found in DEVSIM License. If you would like to participate in this project or need support, please contact us using the information in Contact. Installation instructions may be found in Installation.

2.58.2. Build

The Tcl interpreter version of DEVSIM is now called devsim_tcl, and is located in /src/main/ of the build directory. Please see the INSTALL file for more information.

2.58.3. Contact Material

Contacts now require a material setting (e.g. metal). This is for informational purposes. Contact models still look up parameter values based on the region they are located.

2.58.4. External Meshing

Please see Using an external mesher for more information about importing meshes from other tools.

Genius Mesh Import DEVSIM can now read meshes written from Genius Device Simulator. Support is no longer available in recent versions releases.

Gmsh Mesh Import DEVSIM reads version 2.1 and 2.2 meshes from Gmsh. Version 2.0 is no longer supported. Please see Gmsh for more information.

2.58.5. Math Functions

The acosh, asinh, atanh, are now available math functions. Please see Table 10.2.

2.58.6. Test directory structure

Platform specific results are stored in a hierarchical fashion.