Elimination of numerical underflow in the modelling of optoelectronic devices using multiple precision

In 2D and quasi-3D simulations, Fermi-level pinning of the surfaces has been found to result in the decoupling of the electron and hole populations, preventing numerical convergence to the correct solution. In this work, we report on the elimination of numerical underflow in the self-consistent solution of the Poisson and continuity equations in a 2D optoelectronic device simulator. The use of extended precision to represent the state variables eliminates the numerical underflow and consequently the decoupling of the electron and hole populations.