Localised back contact to ONO passivated c-Si solar cells using laser fired contact method

The localised back contact method for SiO₂/SiN_x/SiO₂ (ONO) back surface passivated crystalline silicon solar cells has been investigated using a 1064 nm Nd:YAG laser. From the quasi-steady-state-photoconductance measurements, feasible passivation properties of effective carrier lifetime (τ_eff), back surface recombination velocity (S_eff) and diffusion length (L_D) with the ONO passivated layer rather than with the SiN_x single layer have been confirmed. Localised point back contacts were formed varying with dot diameter and dot spacing and then the cell performance was characterised from solar simulator measurements. It was confirmed that the cell performance is closely related to the back contact area which is determined by dot diameter and spacing, and dot spacing is the more crucial factor to determine the cell performance than diameter variations.