Limitations of a simplified dangling bond recombination model for a -Si:H

The validity of a widely used simple closed-form expression for the recombination associated with dangling bonds in hydrogenated amorphous silicon (a -Si:H) is linked to the relative position of the distribution of the dangling bond states with respect to the quasi-Fermi levels for trapped electrons and holes. However, these quasi-Fermi levels for traps have not been derived before. In this work, we derive the four relevant quasi-Fermi levels for traps associated with dangling bonds in a -Si:H and clarify the limitations of the simple model.