GSS is a TCAD software that enables two-dimensional numerical simulation of semiconductor device with well-known drift-diffusion and hydrodynamic method. GSS has Basic DDM (drift-diffusion method) solver, Lattice Temperature Corrected DDM solver, EBM (energy balance method) solver and Quantum corrected DDM solver based on density-gradient theory. The GSS program is directed via input statements by a user specified disk file. Supports triangle mesh generation and adaptive mesh refinement. Employs PMI (physical model interface) to support various materials, including compound semiconductor materials such as SiGe and AlGaAs. Supports DC sweep, transient and AC sweep calculations. The device can be stimulated by voltage or current source(s).

GSS is no longer updated, but is still available as open source as a limited edition of the commercial GENIUS TCAD tool. This interface has not been tested with actual ngspice versions and may need some maintainance efforts.