General-purpose Semiconductor Simulator
An open sourced TCAD software






Screen snapshoot



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Important Notice:

We are no longer maintaining the GSS project, due its obsolete design. Users are strongly encouraged to migrate to Genius-Open, which is the open-source edition of the device simulator Genius. Genius-Open is released under GPL. The source code can be downloaded from Cogenda website, or from Github.


GSS is a commercial quality TCAD software which enables two-dimensional numerical simulation of semiconductor device with well-known drift-diffusion and hydrodynamic method. The initial goal of GSS is to provide an efficient tool to calculate the semiconductor device response to the EMP (Electromagnetic Pulse). After two years' hard work, GSS has reached its stable version 0.4x. I published it for attracting more people work with this project.

Fig 1. NMOS transistor and the inner distribution of potential

GSS is an Open Sourced Free Software. The source code is available free of charge under the Free Software BSD license. The code is written in C++ with STL usage. Careful attention is paid to performance related issues.

The software has the following basic features:

  • GSS has Basic DDM (drift-diffusion method) solver, Lattice Temperature Corrected DDM solver, EBM (energy balance method) solver and Quantum corrected DDM solver which based on density-gradient theory. The former 0.37 version has a full HDM (hydrodynamic method) solver.
  • The GSS program is directed via input statements by a user specified disk file. 
  • Support triangle mesh generation and adaptive mesh refinement.
  • Employed PMI (physical model interface) to support various materials, including compound semiconductor materials such as SiGe and AlGaAs.
  • Support DC sweep, transient and AC sweep calculations. The device can be stimulated by voltage or current source(s).
  • Support IV curve automatically trace. (Experimental)
  • Support some advanced features such as high field mobility, impact ionization, band-band tunneling and so on.
  • Support device/circuit mixed simulation (with NGSPICE) via network since version 0.45.
  • 2D and 3D plot capacity for post-process.
  • Process simulation includes thermal diffusion, ion implantation, thermal oxidation.

The examples will give you an image of what GSS can do.


Release 0.47
th June, 2009   (Release Notes)

New features/important changes include:

  • Two demensional process simulation for one demensional mask is added to GSS within GSS-TechSim.
  • GSS-TechSim can be used for simulation of thermal diffusion, ion implantation, thermal oxidation.
  • Process simulation can take the advantages of both analytical solution and numzerical solution of diffusion equations, and it has seen success in simulating bird's beak effect, impurity redistribution effect and some other important phenomenon in semiconductor industry.
  • High dielectric constant materials is added to the material library.
Release 0.46-p11, this is a bug fix update
rd July, 2008   (Release Notes)

New features/important changes include:

  • The damping method is greatly improved. Add automatically time step control to transient analyses.
  • Add Quantum corrected QDDM solver based on density-gradient theory.
  • GSS now use Automatically Differentiation (AD) to calculate Jacobian matrix. Development efficiency is greatly improved. This method is intended to be used in 3D software development.
  • Thanks to AD, the EJ model for mobility and impact ionization calculation has been added to DDML1E/2E with little effort.
  • Newton solver can use extra BnakRose or Potential damping to enhance stability.
  • The obsolete DDML1 and DDML2 solver were removed.
  • The following materials: InAs, InN, InP, InSb, HgCdTe and 3C-SiC have been added to material database.
  • Add optical refraction index to each material.  
  • Some bugs fixed.
  • The completely change log is here.
Release 0.45-p9
rd Dec. 2007

New features/important changes include:

  • DDML1E solver support EJ model for mobility and impact ionization calculation. 
  • The Fermi-Dirac statistic has been implemented in DDML1E.
  • GSS can be invoked by NGSPICE to do device/circuit Mixed-Type simulation. Please refer to the Documentation.
  • Add Hewlett-Packard and Lombardi mobility model to Silicon. Hypertang mobility model to GaAs.
  • Add an electromagnetic solver (using FEM) to simulate optical device such as CCD. This add-on is done by Zhang Xianghua.
  • Add EBML3E solver, which based on energy balance method. Now GSS can simulate short channel MOSFET (channel length ~ 0.1um is ok).
  • Add 1-0.1um NMOS Benchmark.
  • Switch to petsc-2.3.3 and cgnslib-2.5.1
  • Great changes to boundary specification.
  • Some bugs fixed.
Release 0.43-p18
21st April. 2007

New features/important changes include:

  • Add enhanced DDML1E and DDML2E solver, which fully support impact ionization calculation. A DBD (delayed breakdown diode) simulation is added to example.
  • Add AC sweep Solver DDML1AC.
  • Add displacement current calculation for MOS gate.
  • Support transverse electrical field dependent mobility within DDML1E/DDML2E. Add Lucent mobility model to material database. 
  • Support band to band tunneling within DDML1E/DDML2E.
  • Support band gap narrowing due to heavy doping. 
  • Add a GUI text editor which support syntax high light for GSS input file. See the screen snapshoot.
  • Experimental support of VTK plot function.
  • Port to Win32 platform with Cygwin. See download page.
  • Some small bugs fixed.
Release 0.42
7th Sep. 2006

New features/important changes include:

  • Add a mesh generator. Now GSS is no longer dependent on Medici or SGFramework.
  • DDML2 support heterojunction.
  • Add auto configure script.
  • Many bugs fixed.

Release 0.41
4th March. 2006

New features/important changes include:

  • Add a lattice temperature dependent DDM solver (DDML2).
  • Support first and second order transient calculation.
  • Use PMI to support various materials.
  • TIFTOOL, a GUI tool for view Medici/GSS TIF file.
  • Check code with valgrind, many memory bugs fixed.

Pre-release 0.37
Original: 6th July 2005. Patched later.

New features/important changes include:

  • Adaptive mesh refinement.
  • HDM solver uses first or second order finite volume method.
  • Basic DDM solver.
  • Renewed documentation and examples.

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