A kinetic Monte Carlo approach to study transport in amorphous silicon HIT cells

The photogenerated carriers in a-Si/c-Si HIT cells must traverse through the intrinsic amorphous silicon barrier in order to get collected. As this barrier region is amorphous in nature, it contains many defect states and thus the carrier transport is mainly described by defect assisted transport. This work applies the Kinetic Monte Carlo (KMC) method in order to study defect assisted transport by analyzing the interactions between discrete defects and discrete carriers. We explore the 'hopping' nature of transport via defects by considering the effect of phonons. The addition of phonons allows us to study non - iso energetic transitions for injection and extraction of carriers. Once the carriers 'hop' through the barrier they are extracted by mainly three mechanisms, namely, thermionic emission, Poole-Frenkel emission and defect emission. Simulations indicate that Poole - Frenkel emission and thermionic emission are negligible whereas emission of carriers from defects is the dominant mode of extraction.