Physics-based Simulation of III-V Nitride LEDs: The Role of Polarization

This work presents a study of polarization effects in III-V nitride LEDs. The goal is to give a complete overview of the effects caused by built-in polarization in those devices using novel numerical simulation approaches.
The first part describes the internal efficacy in LED devices with different polarization, using a semi-classical approach. For the modeling of the LED structure a semi-classical drift-diffusion model developed within the author's research group is used. The effect of different materials and polarizations on the efficacy is studied. A novel method for improving the efficacy using a quaternary AlInGaN material is proposed.
In the second part a new approach for III-V nitride simulation, implementing Non-Equilibrium Greens Functions (NEGF) is presented. NEGF as a fully quantum mechanical simulation provides a better overview of the spatial and energetic distribution of carriers inside the LED structure, and can be used for detailed understanding of the processes taking place in polar and non-polar devices.