Investigating the Role of Dangling Bond DOS in Dark- and Light-Induced Conductivity of a-Si:H for Photovoltaic Applications

This paper examines the impact of defect-related Density of States (DOS) on both dark and illuminated conductivity of intrinsic amorphous silicon (a-Si:H). The quality of the a-Si:H layer plays a crucial role in achieving high photovoltaic (PV) conversion efficiency, especially when it functions as the absorber layer between two heavily doped regions. Extensive studies have demonstrated that common fabrication processes can introduce a high density of defect states within the bandgap. These defects are typically modeled using two exponentially decaying distributions to represent the valence- and conduction-band tails (BTs), along with two correlated Gaussian distributions accounting for deep defect states associated with dangling bonds (DBs). Based on this model, numerical simulations are carried out by solving the fundamental semiconductor equations—namely Poisson’s equation and the electron and hole continuity equations—in order to analyze how DOS defects affect and govern the electrical conductivity of a-Si:H.