A four-state kinetic model for the carrier-induced degradation in multicrystalline silicon: introducing the reservoir state

In this work, we present new insight into the multi-crystalline silicon carrier-induced defect (CID) by performing multiple degradation and regeneration cycles and further investigation on the partial recovery of mc-CID through extended dark annealing (DA). The maximum normalised defect density was found to decay exponentially with the number of cycles, suggesting that the defect precursors were slowly depleted by DA. A four-state kinetic model is proposed by introducing a reservoir state. Simulation results generated by mathematical modelling based on the proposed state diagrams exhibited good agreement with the experimental results. Extended DA on a partially recovered sample combined with simulation results suggests that the capability of defect formation through DA and the existence of the reservoir state proposed herein were the root causes for the partial recovery reported in the literature. Finally, the change in bound hydrogen state is speculated to cause the modulation of mc-CID formation. A qualitative reservoir model based on the interaction between hydrogen molecules (H₂), boron-hydrogen pairs (B-H) and free hydrogen (H⁺, H°) is proposed and further discussed.