Application of the moving boundary truncated grid method to semiconductor device simulations in the framework of the Boltzmann–Bhatnagar-Gross-Krook equation

An advanced moving boundary truncated grid method is presented as an efficient finite-difference solver for the Boltzmann-Bhatnagar-Gross-Krook equation, specifically tailored for semiconductor device simulations. By dynamically adjusting the computational domain to include only the essential portions of phase space, the truncated grid method significantly reduces computational costs without compromising accuracy. Through this adaptive boundary approach, we integrate the Boltzmann-Poisson system in a GaAs homostructure under various scattering models, including constant relaxation times and polar-optical-phonon scattering, achieving quasiballistic transport simulations at a fraction of the computational expense of conventional methods. Computational results demonstrate that the truncated grid method achieves excellent agreement with full grid solutions, as well as substantial reductions in runtime, and faithfully captures key transport phenomena, such as quasiballistic effects, even in low-density conditions. Adaptability of the truncated grid method across different scattering scenarios, along with its general-purpose applicability, positions it as a robust tool for extending to the full Boltzmann transport equation and quantum kinetic models in future studies.