DEVSIM is a technology computer aided design (TCAD) simulation soft- ware. It is released under an open source license. The software solves user defined partial differential equations (PDEs) on 1D, 2D, and 3D meshes. It is implemented in C++ using custom code and a collection of open source libraries. The Python scripting interface enables users to setup and control their simulations. In this chapter, we present an overview of the tool. This is followed with a bipolar junction transistor (BJT) design and characterization example. A collection of open source tools were used to create a simulation mesh, and visualize results

The simulation files for this paper are available on Github: https://github.com/devsim/devsim_bjt_example This preprint is for a book chapter in: Open Source TCAD/EDA for Compact Modeling, W. Grabinski and D. Tomaszewski, Eds. New York, NY, USA: Springer, 2021 ISBN 978-94-024-1091-4